Plasma kinetics of pipotiazine have been studied in ten schizophrenic patients after oral administration of single dose of pipotiazine at 7 a.m. (30 mg, drops). Peak plasma concentrations are reached one hour after administration (41.8 +/- 19,9 ng/ml) and then rapidly decline until 24 h (2.2 +/- 1.2 ng/ml). During the following days plasma concentrations remain stable at the same sampling times. After 3 days wash-out and first intramuscular injection of pipotiazine palmitate (100 mg) main pharmacokinetic data are found: plasma concentrations of pipotiazine are not detectable during at less 3 days after injection, maximal drug level is attained during second week after i.m. (1.7 +/- 0.9 ng/ml). A period of decline is then recorded. Furthermore the mean ratio between pipotiazine plasma concentration after oral and i.m. administration is about 20. When pipotiazine palmitate is given every fourth week, steady state seems to be reached as early as the second month.