Unfortunately we don't have this as a feature in RadGridView.
I have already scheduled thisone to be added - I believe the most intuitive way would be setting RadGridView.Height to Auto to do the trick. We are going to add this in some of our next releases.
Meanwhile the single workaround I can suggest is to calculate the height and set it explicitly in code behind.
The formula should be something simple like : RadGridView.Height = RowsCount * 24 + HeaderHieght + GroupPanelHeight.
And it may be set within the handler of the DataLoaded event of RadGridView.
the Telerik team