Eighteen patients suffering from an advanced colorectal cancer were treated with 5 days continuous venous infusion of ifosfamide and mesna (1 g/m2, 5/21 days). All had previously received 5-fluorouracil-based chemotherapies. Disposable programmable infusion pumps (Cadd-I, Pharmacia Deltec and Intelliject Multisyringe) allowed ambulatory administration of the treatment. Toxicity was manageable; we had mainly to deplore two cases of grade 3 central nervous system manifestations. Only one minor response (lung lesions) and one no change were evidenced. We conclude that for this type of patient, ifosfamide has very limited antitumor activity. Nevertheless, we demonstrated the safety and feasibility of the proposed ambulatory schedule which could be used in other oncological indications.