Plasma concentrations and renal excretion of 14,15-dihydro-14beta-hydroxy-(3alpha,16alpha)-eburnamenine-14-carbonic acid methylester (vincamine, Vincapront) were studied in 5 healthy volunteers following the oral intake of 30 or 60 mg vincamine, respectively. After the higher dose (60 mg vincamine), the treatment was continued by the daily intake of 3 X 20 mg vincamine for 5 days. Plasma vincamine levels were determined in the morning prior to the ingestion of the first 20-mg dose and in the evening 2 h after the intake of the third 20-mg dose. Our results prove that vincamine is rapidly liberated and absorbed from the tablet formulation used, the maximum plasma levels being reached 90 min after ingestion and amounting to a mean value of 139 ng/ml after 30 mg and to a mean of 252 ng/ml after 60 mg of vincamine. There was a biphasic elimination of vincamine after both doses indicating a process of distribution influencing also the elimination phase. In the 24-h urine, unchanged vincamine amounted to 5.8% of the applied dose after 30 mg and to 7.3% after 60 mg vincamine. Vincamine did not accumulate during the daily intake of 60 mg for 6 days. Side-effects were not observed in any volunteer during the period of observation.