From the DHHS regulations:
6. Ask the donor to:

Remove any unnecessary outer clothing (e.g., coat, jacket, hat, etc.)
The donor must not be asked to remove other articles of clothing, (e.g., shirts, pants, dresses, undergarments) or to remove all clothing and wear a hospital or examination gown.
From § 40.61 the DOT regulations:
You must not ask the employee to remove other clothing (e.g., shirts, pants, dresses, underwear), to remove all clothing, or to change into a hospital or examination gown (unless the urine collection is being accomplished simultaneously with a DOT agency-authorized medical examination).

Sources:
Drug Testing
U.S. Department of Transportation / Office of the Secretary of Transportation
Burnt Toast Reviewed by Burnt Toast on . Hospital Gown required for Pre-employment test?? Has anyone run into this little bump in the road?? I was reading up tonight and I saw it mentioned a couple times that some testing locations will require you to change into a hospital gown in an effort to prevent people from concealing containers of urine and substituting it. In my effort to be prepared for everything, I was wondering a few things about this: 1) Would you be required to take your underwear off? If not, no big deal. I can keep the QF in my undies. If so, then Rating: 5