During the course of a study on the effects of chronic, heavy marijuana use, a placebo control subject reported dizziness and nausea, showed tachycardia and conjunctivitis, and was found to have urinary cannabinoid metabolites. Staff members observing the marijuana smokers also complained of similar subjective symptoms. The detection of cannabinoids in the urine of this nonsmoker documents the previously anecdotal concept of the "contact high" and has implications for marijuana research and for precautions that may be necessary should marijuana become legal.