Experimental and clinical evidence indicates that bleomycin by continuous infusion is superior to intermittent administration. Continuous infusion is less convenient, however. It has been suggested that a suspension of bleomycin in sesame oil, given by IM injection, simulates a continuous infusion. The pharmacokinetics of this formulation have been compared with those of bleomycin in saline following IM injection, in six patients. The pharmacokinetic profiles of the two formulations were similar. The only difference between the profiles was the long terminal half-life at very low concentrations between 12 and 48 h after injection of the oil suspension. This difference is of unknown, but doubtful, clinical significance.