The incidence and clinical features of sarcoidosis were studied in a retrospective survey of 156 patients attending two South London hospitals between 1969 and 1982. Sixty-eight patients were Caucasian, 59 were Black West Indian or African immigrants and 29 were immigrants racially derived from Indo-Pakistan (Asians). The annual incidence of sarcoidosis in the local community in 1977-78 was 19.8 per 10(5) for Blacks and 16.8 per 10(5) for Asians compared with 1.5 per 10(5) for Caucasians. Erythema nodosum was a more common presenting feature in Caucasians than in Blacks (P less than 0.001) or Asians (P less than 0.05). Blacks developed sarcoidosis at a later age than Caucasians (P less than 0.05) and were less likely to present as a chance finding on a chest radiograph (P less than 0.05). They had more widespread extrathoracic disease than Caucasians (P less than 0.001) and were more commonly treated with corticosteroids (P less than 0.001). In the Asians there was a male predominance compared with Caucasians (P less than 0.01). Asians also had more extrathoracic sarcoidosis than Caucasians (P less than 0.001) and more of them were treated with corticosteroids (P less than 0.05). A stage 2 chest radiograph at presentation (P less than 0.05) and skin sarcoidosis (P less than 0.05) were less common in Asians than in Blacks, but otherwise there were no significant differences between the two groups. In this study the incidence of sarcoidosis in Asians approached that in Blacks, while the clinical features were intermediate in severity between Blacks and Caucasians. In both Blacks and Asians the disease was more common, more severe and more extensive than in Caucasians.