Create different options for pasting(keep formatting, merge formatting, use destination styles). At this point, the document default styles are not copied in the document fragment, thus their loss is observed. When DocumentInheritsDefaultStyleSettings is true and the font settings are like set to different font size/font family, copied text is pasted to MS Word with Verdana font, size 12. Loss of formatting is also observed when copying from RadRichTextBox and pasting in MS Word - the default styles differ.