The efficacy of transdermally administered scopolamine was compared with the efficacy of oral dimenhydrinate and placebo therapy in the prevention of motion-induced mausea in a vertical oscillator; medications were administered on a double-blind cross-over basis, with the order of treatments counterbalanced. Thirty-five subjects known to be susceptible to the stimulus were utilized. A placebo effect reduced the motion sickness incidence (MSI) from 100% to 59%. Administration of dimenhydrinate reduced the MSI to 32%, and use of the transdermal therapeutic system scopolamine (TTS-scopolamine) further reduced the MSI TO 16%. TTS-scopolamine afforded 73% protection against motion-induced nausea, compared to 46% protection with dimenhydrinate. The TTS-scopolamine is designed to remain in the body for 72 hours, providing advantages over intramuscular or oral administration of scopolamine, which include reduced daily dosage, and an effective alternate to the gastrointestinal tract for administrating medication at times of gastrointestinal distress.