In CMF regimen, gastric disturbances secondary to oral administration of cyclophosphamide (CTX) frequently induce many patients to take the drug erratically, to lower the daily dose, or to divide it in many administrations. These alterations act as a source of uncertainty in the evaluation of treatment results and may decrease the chemotherapy effectiveness. An i.v. CTX administration is proposed, and the rationale of such a proposal in examined. Data on the mild toxicity of the new schedule are reported.