The pharmacokinetics of ethyl-apovincaminate (vinpocetine, Cavinton), a new vincamine derivative has been studied in volunteers after p.o. and i.v. administration. The concentration of the drug was determined by mass-fragmentography in human plasma. There was a biphasic elimination of the substance after i.v. injection with a T1/2 alpha of 0.136 h and with a T1/2 beta of 4.83 h. The value of Vdss (2.1 l/kg) shows a high adsorption of the drug by tissue proteins. The clearance rate of elimination was 0.366 l/h/kg. Oral administration of the drug resulted in maximum plasma concentration 1--1.5 h after the administration with values of 20--62 ng/ml. The bioavailability of the drug--calculated from the ratio of the areas under the concentration-time curves--proved to be 56.6 +/- 8.9%. Unchanged vinpocetine could not be detected in urine. From the results two-compartment open models were constructed and the steady state concentrations after multiple dosing were computed.