Ifosfamide at 5 g/m2 was given as a bolus to 48 patients with advanced progressing non-small cell lung cancer. Mesna (5 g/m2) was also given with the ifosfamide, both over 30 min. Further mesna was then given p.o. (3 g/m2) at 4, 8, and 12 h. If oral mesna was not acceptable then one or, if necessary, two 4-h to 6-h infusions (3 g/m2) were administered. A maximum of six courses at 3-weekly intervals was prescribed. A total of 174 courses was administered, and oral mesna was given during 64 courses: discharge was considered possible within 8-10 h after 55% of courses. Haematological toxicity was mild and no renal dysfunction was noted. Two patients became drowsy shortly after ifosfamide, but recovered 24-36 h later. The objective response rate was 29%, with one complete responder. A further 31% of patients (symptomatic responders) with stable disease symptomatically improved after the chemotherapy, by 20 or more points on the Karnofsky scale. The median survival was 5 months for the whole group, and 8 months each for the objective and symptomatic responder groups. Most patients' Karnofsky and respiratory scores improved with the chemotherapy. Ifosfamide with mesna can be given by short infusions, and the mesna given p.o. prevents any urothelial toxicity. Further exploration of short-infusion ifosfamide and mesna therapy would reduce hospitalization and allow for day-case regimens.