The clinical pharmacokinetics of a new hypolipidemic drug, procetofene (Lipanthyl), have been determined in 10 normolipemic volunteers after a single 300 mg dose and repeated 300 mg fractioned doses (b.i.d.) during 10 days, followed by an additional single dose (300 mg) on day 11. The peak plasma level of procetofenic acid, the circulating active metabolite, was observed after 4 or 6 hr. A steady-state plasma level above 10 microgram/ml was reached on day 5 and maintained to day 10 on continued fractioned administration. This mean plasma level was not reached during the single-dose study. A double-exponential plasma decay curve was observed in volunteers after repeated doses: alpha phase, 5.27 +/- 1.05 hr; beta phase, 21.73 +/- 1.07 hr. As shown by the urinary excretion data, the drug is poorly absorbed by the digestive tract, i.e., only about 30% is absorbed.