Although cocaine is a potent serotonin reuptake blocker, the role of 5-HT systems in cocaine craving and relapse in humans is unclear. Satel et al (1995, American Journal of Psychiatry) evaluated whether acute reductions in central 5-HT synthesis modulated craving for cocaine in cocaine-dependent patients. Craving was induced by exposure to cocaine paraphernalia and a videotape depicting drug use. Visual analog ratings of craving for cocaine were administered before and after cue exposure at each test session. Patients reported less desire for cocaine stimulated by cue exposure after ATD than they did after drinking the balanced control mixture. Serotonergic systems modulate cue-induced craving for cocaine, a factor implicated in relapse to cocaine use.