A single oral dose of 6 mg phenylbutazone/kg body wt. was administered to seven cigarette smokers and to seven healthy male volunteers serving as control. Plasma phenylbutazone half-life (t1/2 beta) was shortened significantly (p less than 0.05) in the cigarette smokers as compared to the non-smoker control group. Phenylbutazone was cleared from the blood significantly faster (p less than 0.06) in the smoking group than in the non-smoking group.