Multivariate analysis of prognostic factors for 458 patients with metastatic non-seminomatous germ-cell testicular tumours treated with chemotherapy between 1976 and 1982 in 6 British centres showed a 3-year survival rate of 75%. 3 prognostic groups with survival rates of 91%, 72%, and 47% could be identified by means of tumour volume, serum alphafetoprotein, and human chorionic gonadotropin concentrations. Patient age and year in which the chemotherapy was given were additional variables independently related to outcome. Delay from first symptom to start of treatment was related to tumour volume and marker levels as well as survival time and is an important potentially reversible determinant of long-term survival. This study provides the basis for defining subgroups for future randomised trials and suggests that tumour volume and serum marker levels are important and complementary as prognostic indicators.