ok... apparently you were right, both of you...It seems to always antialias over black background color when I use the following parameters : Display / Preview Drawing / Open GL Softaware. But it works perfectly when I choose these parameters : Display / Preview Drawing / SreeD Software... Perhaps someone can explain the reason of this... Is it impossible to antialias a document over a custom background color when using the Open GL Software ?? Nethertheless thank for your answers, guys :)