In a survey of the chemotherapy prescribed for 1312 adult patients of white or Indian subcontinent ethnic origin with pulmonary tuberculosis only, notified in the 6 months from October 1978 to March 1979, it was found that 163 (12%) patients died before they had completed chemotherapy. Of the 163 patients who died 96% were of white ethnic origin; 15% of the 1022 white patients died compared with 2% of the 290 Indian subcontinent patients. According to the death certificate, approximately half the white patients died from tuberculosis, and in a further 31% tuberculosis was a contributory factor. Death from tuberculosis most frequently occurred in the older age groups, accounting in part for the different findings in these two ethnic groups, because of the excess of older white patients. In a step-wise multivariate discriminant analysis death from tuberculosis was found to be significantly associated in the white patients with the radiographic extent of disease before treatment, and with age, extent of cavitation and a positive sputum smear result, but not sex. Most of the deaths from tuberculosis occurred early, 38% before the end of the first week of chemotherapy and 69% by the end of 4 weeks. There was a further group of 51 adult patients with pulmonary tuberculosis notified in the same 6-month period in whom the diagnosis was not made until after death, 25 of them dying from tuberculosis. It is concluded that there is still a substantial risk of death from tuberculosis in patients with extensive disease in the older age groups.