The single-dose pharmacokinetics of N-benzyl-2-nitro-1-imidazole acetamide (benznidazole, Radanil) following administration of 1 tablet Radanil (100 mg) was investigated in six healthy volunteers. The absorption of the drug was fairly rapid. Peak plasma levels of 2.2--2.8 microgram/ml were reached after 3--4 h. The log c versus time curves showed little interindividual variation. The shape of the curves indicates that the drug follows the kinetics of a one-compartment model. The elimination half-lives ranged from 10.5 to 13.6 h, with a mean value of 12 h. The relative bioavailability of the compound (oral tablet versus oral solution) was checked in three of the subjects and found to be 91.7% on an average.