A 59-year-old man with pulmonary blastoma, who had undergone right-sided pneumonectomy, had a relapse of the tumour 7 months later. Light-microscopic and ultrastructural studies were consistent with recurrence from the primary tumour. Cell kinetic studies revealed a high fraction of tumour cells in the S-phase. Complete remission of the recurrence was obtained within 16 days after initiation of combination chemotherapy consisting of CCNU, vincristine, VP-16 and cyclophosphamide.