they'll tell you what they're testing you before they do the test. on a standard test however, i believe they test for weed, herion, crack/coke, and methamphetamines... on the more extensive (and more expensive) tests, i know they test for just about everything that's a street drug (i.e. they dont' test for robo or shit like that, but they do test for xanax, valium, vicodin and so on)