Forty-four patients with small cell lung cancer (SCLC), who were working in some kind of profession when they were taken ill, were studied with regard to return to work during or after cancer treatment. All patients received combination chemotherapy without chest radiotherapy or prophylactic brain irradiation. Twelve patients, referred to as W, returned to work during some period (14-83 weeks) after commencement of treatment, and 32 did not (NW). The stage of the disease prior to treatment and the type of profession seemed to be major prognostic factors. Patients with limited disease or "light" occupations more often returned to work than did patients with extensive disease or "heavy" occupations (P = 0.027 and 0.037, respectively). Age, sex and performance status were less important factors. Long-term survival was not a necessary condition for return to work, and overall survival was not prolonged in W patients compared with NW patients. It is concluded that increased occupational activity is an important palliative gain from chemotherapy in SCLC, and that this gain is not confined to a specific subgroup of patients, but is most likely to occur in patients with limited disease.