The clinical pharmacology of bleomycin administered as an i.v. bolus was studied in a homogeneous group of patients with testicular carcionoma receiving a single regimen containing bleomycin, vinblastine and cis-dichlorodiammineplatinum(II). In patients with creatinine clearances .gtoreq. 35 ml/min, the serum (or plasma) terminal elimination half-life of bleomycin was approximately 115 min. In patients with creatinine clearances < 25-35 ml/min, the terminal elimination half-life increased exponentially as the creatinine clearances decreased. The volume of distribution was approximately 20 l, and was unaffected by changes in creatinine clearance. The microbiologic assay and radioimmunoassay employed gave equivalent results.