1 Absorption, excretion and detoxification of temazepam were investigated in man, mouse, rat and dog. Considerable interspecies variation was apparent with respect to excretion and metabolite patterns in blood and urine. Animal species were exposed to equal or greater concentrations of all the metabolites occurring in man. 2 Pharmacokinetics of temazepam in man were investigated in a single dose study at two dose levels, and in a multiple dose study. The results of both studies were analyzed and interpreted with the help of compartmental models. Values were obtained for excretion pattern (0-infinity), half lives (1.95, 0.5, 10.0 and 1.9 h), amounts in all compartments, and for steady-state conditions. 3 The bioavailability of the hard gelatin capsule dosage form was compared with that of a suspension serving as the ideal dosage form, and found to be acceptable.