From January 1986 through December 1988, 227 patients were included in a multi-institutional pilot study for small cell lung cancer (SCLC). Out of the 211 patients who fully completed the staging procedures, 77 (35%) appeared to have SCLC limited to the thorax. All patients received combination therapy consisting of AVI (Adriamycin, VP-16 and Ifosfamide), except during radiotherapy when the Adriamycin was omitted, plus twice daily fractionated 18 MV radiotherapy. Treatment protocol consisted of 4 initial courses of AVI, followed by 3 courses of radiotherapy alternating with modified chemotherapy (VP-16 and Ifosfamide), completed by 2 courses of initial chemotherapy (AVI). Radiotherapy consisted of 1.5 Gy/fraction, 2 fractions/day, 5 days/week in the first course, and 1.8 Gy/fraction, 2 fractions/day, 5 days/week, in the second and third courses, for a total tumor dose of 51 Gy, felt to be equivalent to 60 Gy at normal fractionation. CT treatment planning was employed to design a treatment consisting of multiport radiotherapy, using AP-PA and laterals or obliques beams. During the first course, the homolateral hemithorax received 9 Gy total dose on days 1, 3, 5. During the third course, 360 degrees arctherapy was generally used to boost the reduced tumor volume to a 51 Gy. Besides chest X ray and CT scan, staging and restaging procedures included fiberoptic bronchoscopy. Response rate after irradiation is 61%, with 46% complete responders and 51% local control. The median survival is 14 months, and disease-free survival 42% at 1 year. Complications consisted of cardiac toxicity in 2 patients, 1 death of acute pulmonary toxicity, and 4 instances of moderate chronic radiation pneumonitis. Thus, high doses of radiation can be delivered combined with chemotherapy using this protocol, with an acceptable toxicity and encouraging results in response rate and local control. A longer follow-up is needed to evaluate the impact of these results on survival.