The pharmacokinetics of bendamustine (Cytostasane) was determined in plasma on seven patients after its intravenously and oral application, respectively. Cytostasane was given in a dosis of 4.2-5.5 mg . kg-1 as an intravenous infusion over 3 min and as gelatine capsules in a 7-d intervall. Its elimination from the plasma is fast, monoexponentially and two-phasic after intravenous application (t1/2 alpha = 9.6 min, t1/2 beta = 36.1 min). The AUC was 11.17 micrograms . ml-1 . h, the central distribution volume 11.15 l and the distribution volume in steady state 20.51 l. The mean total clearance was 528.9 ml . min-1. After oral application maximal plasma levels of Cytostasane were detectable before 1 h. The mean oral bioavailability was 0.57, ranged from 0.25 to 0.94. Cytostasane undergoes metabolism. Its hydrolysis in plasma is slow (t1/2 = 1.67 h). After Cytostasane the depression of leucocytes was mild.