diff --git a/lib/recurly/invoice.rb b/lib/recurly/invoice.rb
index 00851ebae..cac806c93 100644
--- a/lib/recurly/invoice.rb
+++ b/lib/recurly/invoice.rb
@@ -249,6 +249,25 @@ def refund_amount(amount_in_cents = nil, refund_method = 'credit_first', options
       )
     end
 
+    # Refunds the invoice for a specific percentage.
+    #
+    # @return [Invoice, false] Invoice if successful, false if the invoice isn't
+    # refundable.
+    # @raise [Error] If the refund fails.
+    # @param percentage [Integer, nil] The percentage to refund from the invoice.
+    # @param refund_method ["credit_first", "transaction_first", "all_transaction", "all_credit"] The method used to refund.
+    # @param external_refund [true, false] Designates that the refund transactions created are manual.
+    # @param credit_customer_notes [String] Adds notes to refund credit invoice.
+    # @param payment_method [String] Creates the manual transactions with this payment method. Allowed if *external_refund* is true.
+    # @param description [String] Sets this value as the *transaction_note* on the manual transactions created. Allowed if *external_refund* is true.
+    # @param refunded_at [DateTime] Sets this value as the *collected_at* on the manual transactions created. Allowed if *external_refund* is true.
+    def refund_percentage(percentage = nil, refund_method = 'credit_first', options = {})
+      return false unless link? :refund
+      self.class.from_response(
+        follow_link :refund, :body => refund_percentage_to_xml(percentage, refund_method, options)
+      )
+    end
+
     def xml_keys
       super - ['currency']
     end
@@ -285,6 +304,16 @@ def refund_amount_to_xml(amount_in_cents = nil, refund_method = nil, options = {
       builder.to_s
     end
 
+    def refund_percentage_to_xml(percentage = nil, refund_method = nil, options = {})
+      builder = XML.new("<invoice/>")
+      builder.add_element 'refund_method', refund_method
+      builder.add_element 'percentage', percentage
+      options.each do |k, v|
+        builder.add_element k.to_s, v
+      end
+      builder.to_s
+    end
+
     def refund_line_items_to_xml(line_items = nil, refund_method = nil, options = {})
       builder = XML.new("<invoice/>")
       builder.add_element 'refund_method', refund_method
@@ -296,8 +325,10 @@ def refund_line_items_to_xml(line_items = nil, refund_method = nil, options = {}
       line_items.each do |line_item|
         adj_node = node.add_element 'adjustment'
         adj_node.add_element 'uuid', line_item[:adjustment].uuid
-        adj_node.add_element 'quantity', line_item[:quantity]
+        adj_node.add_element 'quantity', line_item[:quantity] if line_item.key?(:quantity)
         adj_node.add_element('quantity_decimal', line_item[:quantity_decimal]) if line_item.key?(:quantity_decimal)
+        adj_node.add_element 'percentage', line_item[:percentage] if line_item.key?(:percentage)
+        adj_node.add_element 'amount_in_cents', line_item[:amount_in_cents] if line_item.key?(:amount_in_cents)
         adj_node.add_element 'prorate', line_item[:prorate]
       end
       builder.to_s
diff --git a/spec/recurly/invoice_spec.rb b/spec/recurly/invoice_spec.rb
index 155a6e11e..fb30c87b3 100644
--- a/spec/recurly/invoice_spec.rb
+++ b/spec/recurly/invoice_spec.rb
@@ -162,6 +162,22 @@
           adjustment.quantity_remaining.must_equal 1
         end
       end
+
+      it "creates a refund invoice for the line items refunded with amount in cents" do
+        line_items = @invoice.line_items.values.map do |adjustment|
+          { adjustment: adjustment, amount_in_cents: 100, prorate: false }
+        end
+        refund_invoice = @invoice.refund line_items
+        refund_invoice.must_be_instance_of Invoice
+      end
+
+      it "creates a refund invoice for the line items refunded with percentage" do
+        line_items = @invoice.line_items.values.map do |adjustment|
+          { adjustment: adjustment, percentage: 77, prorate: false }
+        end
+        refund_invoice = @invoice.refund line_items
+        refund_invoice.must_be_instance_of Invoice
+      end
     end
 
     describe "#refund_to_xml" do
@@ -178,6 +194,38 @@
           '<invoice><refund_method>credit_first</refund_method><credit_customer_notes>Credit Notes</credit_customer_notes><external_refund>true</external_refund><payment_method>check</payment_method><description>Check no. 12345678</description><refunded_at>2018-12-01T00:00:00+00:00</refunded_at><amount_in_cents>17500</amount_in_cents><line_items><adjustment><uuid>charge1</uuid><quantity>1</quantity><prorate>false</prorate></adjustment></line_items></invoice>'
         )
       end
+
+      it "must serialize line_items with amount_in_cents" do
+        line_items = @invoice.line_items.values.map do |adjustment|
+          { adjustment: adjustment, amount_in_cents: 100, prorate: false }
+        end
+        options = {
+          credit_customer_notes: 'Credit Notes',
+          external_refund: true,
+          payment_method: 'check',
+          description: 'Check no. 12345678',
+          refunded_at: DateTime.new(2018, 12, 1, 0, 0, 0)
+        }
+        @invoice.send(:refund_line_items_to_xml, line_items, 'credit_first', options).must_equal(
+          '<invoice><refund_method>credit_first</refund_method><credit_customer_notes>Credit Notes</credit_customer_notes><external_refund>true</external_refund><payment_method>check</payment_method><description>Check no. 12345678</description><refunded_at>2018-12-01T00:00:00+00:00</refunded_at><line_items><adjustment><uuid>charge1</uuid><amount_in_cents>100</amount_in_cents><prorate>false</prorate></adjustment></line_items></invoice>'
+        )
+      end
+
+      it "must serialize line_items with percentage" do
+        line_items = @invoice.line_items.values.map do |adjustment|
+          { adjustment: adjustment, percentage: 77, prorate: false }
+        end
+        options = {
+          credit_customer_notes: 'Credit Notes',
+          external_refund: true,
+          payment_method: 'check',
+          description: 'Check no. 12345678',
+          refunded_at: DateTime.new(2018, 12, 1, 0, 0, 0)
+        }
+        @invoice.send(:refund_line_items_to_xml, line_items, 'credit_first', options).must_equal(
+          '<invoice><refund_method>credit_first</refund_method><credit_customer_notes>Credit Notes</credit_customer_notes><external_refund>true</external_refund><payment_method>check</payment_method><description>Check no. 12345678</description><refunded_at>2018-12-01T00:00:00+00:00</refunded_at><line_items><adjustment><uuid>charge1</uuid><percentage>77</percentage><prorate>false</prorate></adjustment></line_items></invoice>'
+        )
+      end
     end
   end
 
@@ -189,8 +237,8 @@
       @invoice = Invoice.find 'refundable-invoice'
     end
 
-    describe "#refund" do
-      it "creates a refund invoice for the line items refunded" do
+    describe "#refund_amount" do
+      it "creates a refund invoice for the line items refunded using amount" do
         refund_invoice = @invoice.refund_amount 1000
         refund_invoice.must_be_instance_of Invoice
         refund_invoice.original_invoices.must_be_instance_of Recurly::Resource::Pager
@@ -198,7 +246,7 @@
       end
     end
 
-    describe "#refund_to_xml" do
+    describe "#refund_amount_to_xml" do
       it "must serialize amount_in_cents" do
         options = {
           credit_customer_notes: 'Credit Notes',
@@ -215,6 +263,39 @@
     end
   end
 
+  describe "percentage refund" do
+    before do
+      stub_api_request :get, 'invoices/refundable-invoice', 'invoices/show-200-refundable'
+      stub_api_request :post, 'invoices/refundable-invoice/refund', 'invoices/refund_amount-201'
+
+      @invoice = Invoice.find 'refundable-invoice'
+    end
+
+    describe "#refund_percentage" do
+      it "creates a refund invoice for the line items refunded using percentage" do
+        refund_invoice = @invoice.refund_percentage 50
+        refund_invoice.must_be_instance_of Invoice
+        refund_invoice.original_invoices.must_be_instance_of Recurly::Resource::Pager
+        refund_invoice.amount_remaining_in_cents.must_equal 100
+      end
+    end
+
+    describe "#refund_percentage_to_xml" do
+      it "must serialize percentage" do
+        options = {
+          credit_customer_notes: 'Credit Notes',
+          external_refund: true,
+          payment_method: 'check',
+          description: 'Check no. 12345678',
+          refunded_at: DateTime.new(2018, 12, 1, 0, 0, 0)
+        }
+        @invoice.send(:refund_percentage_to_xml, 50, 'credit_first', options).must_equal(
+          '<invoice><refund_method>credit_first</refund_method><percentage>50</percentage><credit_customer_notes>Credit Notes</credit_customer_notes><external_refund>true</external_refund><payment_method>check</payment_method><description>Check no. 12345678</description><refunded_at>2018-12-01T00:00:00+00:00</refunded_at></invoice>'
+        )
+      end
+    end
+  end
+
   describe "failed_refund" do
     before do
       stub_api_request :get, 'invoices/refundable-invoice', 'invoices/show-200-refundable'