Continuous intravenous infusion of anticancer drugs is being incorporated into more experimental chemotherapy protocols. The rationale for use of continuous infusions generally includes the restriction of cytotoxic mechanisms of a drug to a specific phase of the cell cycle and the short half-life of some drugs. Two such agents are cytarabine and bleomycin; continuous exposure to these drugs greatly increases their antitumor effects in cell cultures and animal models. Toxicity to normal tissues may also be reduced by continuous infusion, notably the pulmonary toxicity of bleomycin, the cardiac toxicity of doxorubicin, and the myelosuppression of fluorouracil. Recent advances in infusion pump technology have made continuous intravenous infusion therapy more practical. Unfortunately, most clinical studies of the continuous infusion of anticancer drugs have been uncontrolled. Further randomized, controlled clinical trials comparing schedules of drug administration are necessary before definitive recommendations can be made.