Heavy chronic consumption of kava (Piper methysticum) is associated with a pellagroid dermopathy that has been attributed to niacin deficiency. Over 200 male kava drinkers in the Tonga Islands were interviewed and examined regarding the characteristic skin changes. A scaly rash suggestive of ichthyosis and eye irritation were present in some heavy kava drinkers. 29 kava drinkers with prominent skin changes were randomised to receive either 100 mg oral nicotinamide or placebo daily for three weeks. Skin examinations and photographs showed clinical improvement in 5/15 of the nicotinamide group and 5/14 of the placebo group. These data, along with history and physical examination findings, suggest that niacin deficiency is not responsible for the rash, which is more characteristic of an acquired ichthyosis.