Set the Stroke color and size for Ellipse
<UserControl x:Class='SilverlightApplication3.MainPage' xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation' xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml' xmlns:d='http://schemas.microsoft.com/expression/blend/2008' xmlns:mc='http://schemas.openxmlformats.org/markup-compatibility/2006' mc:Ignorable='d' d:DesignWidth='640' d:DesignHeight='480'> <Canvas x:Name="LayoutRoot" Background="White" > <Ellipse Width="150" Height="150" Fill="Black" Stroke="Red" StrokeThickness="5"/> </Canvas> </UserControl>