Kent Boogaart have written an article that describe approach searching and highlighting text in FlowDocumentPageViewer - Search and Highlight Text in an Arbitrary Visual Tree. Unfortunate, two serious issues present there. I copy theirs description from msdn forum: 1. When I change the pages of the FlowDocumentPageViewer, my Rectangular highlighted area remains the same and it is not sinking with the Text. 2. When I zoom in or zoom out of the FlowDocumentPageViewer, the text gets zoomed but the Highlight rectangle remains in the same position.