Index: app/helpers/custom_fields_helper.rb
===================================================================
--- app/helpers/custom_fields_helper.rb	(revision 17628)
+++ app/helpers/custom_fields_helper.rb	(working copy)
@@ -180,4 +180,48 @@
     end
     form.select :edit_tag_style, select_options, :label => :label_display
   end
+
+  def render_api_issue_custom_field(field, api)
+    api.custom_field do
+      api.id                field.id
+      api.name              field.name
+      api.customized_type   field.class.customized_class.name.underscore if field.class.customized_class
+      api.field_format      field.field_format
+      api.regexp            field.regexp
+      api.min_length        field.min_length
+      api.max_length        field.max_length
+      api.is_required       field.is_required?
+      api.is_filter         field.is_filter?
+      api.searchable        field.searchable
+      api.multiple          field.multiple?
+      api.default_value     field.default_value
+      api.visible           field.visible?
+
+      values = field.possible_values_options
+      if values.present?
+        api.array :possible_values do
+          values.each do |label, value|
+            api.possible_value do
+              api.value value || label
+              api.label label
+            end
+          end
+        end
+      end
+
+      if field.is_a?(IssueCustomField)
+        api.array :trackers do
+          field.trackers.each do |tracker|
+            api.tracker :id => tracker.id, :name => tracker.name
+          end
+        end
+        api.array :roles do
+          field.roles.each do |role|
+            api.role :id => role.id, :name => role.name
+          end
+        end
+      end
+    end
+  end
+
 end
Index: app/views/custom_fields/index.api.rsb
===================================================================
--- app/views/custom_fields/index.api.rsb	(revision 17628)
+++ app/views/custom_fields/index.api.rsb	(working copy)
@@ -1,44 +1,5 @@
 api.array :custom_fields do
   @custom_fields.each do |field|
-    api.custom_field do
-      api.id                field.id
-      api.name              field.name
-      api.customized_type   field.class.customized_class.name.underscore if field.class.customized_class
-      api.field_format      field.field_format
-      api.regexp            field.regexp
-      api.min_length        field.min_length
-      api.max_length        field.max_length
-      api.is_required       field.is_required?
-      api.is_filter         field.is_filter?
-      api.searchable        field.searchable
-      api.multiple          field.multiple?
-      api.default_value     field.default_value
-      api.visible           field.visible?
-
-      values = field.possible_values_options
-      if values.present?
-        api.array :possible_values do
-          values.each do |label, value|
-            api.possible_value do
-              api.value value || label
-              api.label label
-            end
-          end
-        end
-      end
-
-      if field.is_a?(IssueCustomField)
-        api.array :trackers do
-          field.trackers.each do |tracker|
-            api.tracker :id => tracker.id, :name => tracker.name
-          end
-        end
-        api.array :roles do
-          field.roles.each do |role|
-            api.role :id => role.id, :name => role.name
-          end
-        end
-      end
-    end
+    render_api_issue_custom_field field, api
   end
 end
Index: app/views/projects/show.api.rsb
===================================================================
--- app/views/projects/show.api.rsb	(revision 17628)
+++ app/views/projects/show.api.rsb	(working copy)
@@ -11,6 +11,14 @@
   render_api_custom_values @project.visible_custom_field_values, api
   render_api_includes(@project, api)
 
+  api.array :issue_custom_fields do
+    @project.all_issue_custom_fields.each do |field|
+      if field.visible_by? @project
+        render_api_issue_custom_field field, api
+      end
+    end
+  end if include_in_api_response?('issue_custom_fields')
+
   api.created_on @project.created_on
   api.updated_on @project.updated_on
 end
Index: test/integration/api_test/projects_test.rb
===================================================================
--- test/integration/api_test/projects_test.rb	(revision 17628)
+++ test/integration/api_test/projects_test.rb	(working copy)
@@ -138,6 +138,26 @@
     assert_select 'enabled_modules[type=array] enabled_module[name=issue_tracking]'
   end
 
+  test "GET /projects/:id.xml with include=issue_custom_fields should return issue custom fields" do
+    get '/projects/1.xml?include=issue_custom_fields'
+    assert_response :success
+    assert_equal 'application/xml', @response.content_type
+
+    assert_select 'issue_custom_fields' do
+      assert_select 'custom_field' do
+        assert_select 'name', :text => 'Database'
+        assert_select 'id', :text => '2'
+        assert_select 'customized_type', :text => 'issue'
+        assert_select 'possible_values[type=array]' do
+          assert_select 'possible_value>value', :text => 'PostgreSQL'
+          assert_select 'possible_value>label', :text => 'PostgreSQL'
+        end
+        assert_select 'trackers[type=array]'
+        assert_select 'roles[type=array]'
+      end
+    end
+  end
+
   test "POST /projects.xml with valid parameters should create the project" do
     with_settings :default_projects_modules => ['issue_tracking', 'repository'] do
       assert_difference('Project.count') do