An estimated 1 in 4 women in the United States will be raped in their lifetimes. Approximately 75% of all rapes are date or acquaintance rapes. Recently the illegal use of flunitrazepam (Rohypnol), a benzodiazepine, as a prelude to the assault has been reported. Flunitrazepam readily dissolves, and once in solution, is colorless, odorless, and tasteless. The predominant clinical manifestations are drowsiness, impaired motor skills, and anterograde amnesia. Due to the amnestic effects of flunitrazepam, historical clues of the rape event are difficult to obtain. Patients with a complaint of sexual assault who appear intoxicated or have anterograde amnesia should be suspected of unknowingly ingesting flunitrazepam. In addition to adhering to standard rape protocols, a urine specimen should be analyzed for flunitrazepam metabolites using gas chromatography/mass spectrometry. If the hospital, local, or forensic laboratory is unable to analyze for flunitrazepam, Hoffmann-La Roche Inc., the manufacturer of Rohypnol, should be contacted. Hoffmann-La Roche has a mechanism for definitive testing for flunitrazepam, at no cost, for health care providers, rape treatment centers, and law enforcement agencies. A network of organizations is attempting to reduce the abuse of flunitrazepam in association with date rape.