In a double-blind randomized placebo trial, the effect of the powdered rhizome of ginger (Zingiber officinale) was tested on seasickness. Eighty naval cadets, unaccustomed to sailing in heavy seas reported during voyages on the high seas, symptoms of seasickness every hour for 4 consecutive hours after ingestion of 1 g of the drug or placebo. Ginger root reduced the tendency to vomiting and cold sweating significantly better than placebo did (p less than 0.05). With regard to vomiting, a modified Protection Index (PI) = 72% was calculated. Remarkably fewer symptoms of nausea and vertigo were reported after ginger root ingestion, but the difference was not statistically significant. For all symptom categories, PI = 38% was calculated.