The efficacy of transdermal scopolamine, oral meclizine, and placebo in protection against motion sickness was compared in a double-blind crossover study. Thirty-six healthy subjects were exposed to motion three times for 90 min in a ship-motion simulator. Transdermal applications were made and tablets were taken at least 12 and 2 hr before exposure to motion. Transdermal scopolamine provided better protection than placebo or meclizine. Dryness of mouth was the only side effect reported more frequently for one regimen, transdermal scopolamine.