Question: I have a gridview that I wish to display gridlines only on certain rows.

I want them to be on each column, but only after every 4 rows. Is this possible?

Thanks.

Answer: 
You can use the DataGridView.CellPainting event.
You can always user javascript (JQuery) to select wanted columns on table generated by gridview asp.net. After selecting this columns, set their right-border to wanted value or color.

If you don't want to use javascript, you can use RowDataBound eventHandler. If your columns are template fields, you can find wanted control ( e.Row.FindControl("ControlName")) and it's parent ( e.Row.FindControl("ControlName").Parent ). I am not sure, but I think that parent should be wanted cell and then you can set borders. You can try something like this, I haven't tried this.