A meta-analysis was carried out on the studies of chemotherapy of non small cell bronchial cancer published over the last fifteen years and this has demonstrated that the initial extent of the tumour was a significant prognostic factor in the response to treatment. A total of 6,247 patients were eligible for analysis: 1,435 with limited disease and 4,812 with disseminated disease. The objective and complete response levels for the overall group for those with limited disease and those with disseminated disease were respectively 25 and 3%, 34 and 5% and 22 and 3%. These differences were highly significant. The response level was significantly lower in cases of monotherapy when compared to combinations of cytostatic agents. In polychemotherapy, it was those combinations containing cisplatin, vindesine, vinblastine, mitomycin C and ifosfamide which were associated with the best results. An elevated dose of cisplatin (greater than or equal to 100 mg/m2) was also associated with a better response than those on the lower dose (less than or equal to 70 mg/m2). These differences were most clearly shown in those with limited disease.