Forms Data Controls :: Level Breaks In A Gridview Control?

I have a gridview on my asp.net web page. I bind the gridview to a dataset. The dataset has the following fields:

facility, date, patient name, description. Presently, the gridview looks like this when rendered:

ABC Hospital 10/1/2009 John Doe Sore Throat
ABC Hospital 10/2/2009 Jane Doe Mumps
ABC Hospital 10/3/2009 Bill Smith Flu
XYZ Hospital 10/2/2009 Tom Jones Migraine
XYZ Hospital 10/2/2009 Mary Mills Cold

I would like to ony display the facility once for each group. For example, ABC Hospital would only display on the first line and would be blank on the next 2 lines. I think I did this once before but cannot find the code. I have not been able to find a good example on the web.