diff --git app/models/query.rb app/models/query.rb
index f3b83d0..f61e9ce 100644
--- app/models/query.rb
+++ app/models/query.rb
@@ -469,8 +469,8 @@ class Query < ActiveRecord::Base
       if has_filter?("subproject_id")
         case operator_for("subproject_id")
         when '='
-          # include the selected subprojects
-          ids += values_for("subproject_id").each(&:to_i)
+          # include the selected subprojects, but not the parent project.
+          ids = values_for("subproject_id").each(&:to_i)
         when '!*'
           # main project only
         else
diff --git config/locales/de.yml config/locales/de.yml
index ea60e80..48bc15f 100644
--- config/locales/de.yml
+++ config/locales/de.yml
@@ -293,7 +293,7 @@ de:
   field_comments: Kommentar
   field_url: URL
   field_start_page: Hauptseite
-  field_subproject: Unterprojekt von
+  field_subproject: Unterprojekt
   field_hours: Stunden
   field_activity: Aktivität
   field_spent_on: Datum
diff --git test/unit/query_test.rb test/unit/query_test.rb
index e3f3c92..c004acb 100644
--- test/unit/query_test.rb
+++ test/unit/query_test.rb
@@ -62,6 +62,24 @@ class QueryTest < ActiveSupport::TestCase
   def assert_query_statement_includes(query, condition)
     assert query.statement.include?(condition), "Query statement condition not found in: #{query.statement}"
   end
+
+  def test_filter_subproject_should_not_include_parent_issues
+    User.current = User.find(1)
+    project = Project.find(1)
+    assert project.issues.any?
+    subproject = project.children.find(3)
+    assert subproject.issues.any?
+    query = Query.new(:name => '_',
+                      :project => project,
+                      :filters => { 'subproject_id' => {:operator => '=', :values => [3]}})
+    result = find_issues_with_query(query)
+    assert_not_nil result
+    assert_equal subproject.issues.size, result.size
+    result.each do |issue|
+      assert_equal 3, issue.project_id
+    end
+    User.current = nil
+  end
   
   def assert_query_result(expected, query)
     assert_nothing_raised do