The pharmacokinetics of triglycyl-lysine-vasopressin (TGLVP) were studied in healthy male volunteers after single i.v. injections of 5, 10 and 20 micrograms/kg b. wt. The half-life of distribution and elimination was 8 and 50 min, respectively. The volume of distribution was 0.7 l/kg b.wt. and the plasma clearance 9 ml/kg b.wt./min. These values are different from those for arginine-vasopressin and lysine-vasopressin (LVP) but confirm to some extent earlier results on TGLVP. No dose-dependent changes of the pharmacokinetics of TGLVP were evident. The LVP formation after TGLVP is described in principle using a combination of pharmacokinetic and pharmacodynamic data. Therapeutically the results in this study suggest a 4-hour interval between injections.