The prevalence of diagnosed systemic lupus erythematosus (SLE) during 1989 in the adult Indian Asian and White populations of the city of Leicester has been determined. Fifty cases (19 Asian, 31 White) fulfilling the 1982 revised ARA criteria for SLE were identified from a population of 191,469 (37,684 Asian, 153,785 White). Five different sources were used to ascertain cases. The overall prevalence of SLE in Whites was 20.2 per 100,000. Asians of both sexes had a significantly higher prevalence than Whites. Prevalence in males was 31.5 and 7.0 per 100,000 in Asians and Whites respectively; in females the figures were 69.7 and 31.7 per 100,000. Overall, lupus was 3.0 times more common in Asians than Whites. This is the first prevalence study of SLE in Indian Asians and suggests that, like the Black races and the Chinese, they have a greater frequency of SLE than Whites.