A 36-year-old male became intoxicated from fentanyl by heating and inhaling the contents from a fentanyl patch. He collapsed immediately after one inhalation with a respiratory rate of 6/m, heart rate of 120 bpm, and unobtainable blood pressure. He responded to a naloxone injection. Inhalation abuse of fentanyl base is a novel phenomenon. In two studies of nebulized fentanyl at doses of 64-318 micrograms of fentanyl base, analgesia was achieved with these doses, and small decreases in respiratory rate occurred with the larger dose. The greater absorption expected from inhaling the volatilized product, the large quantity of fentanyl available in a patch, and the high potency of fentanyl produces a high potential for abuse and overdose.