The prevalence of islet cell antibodies (ICA and CF-ICA) together with other organ-specific auto-antibodies was investigated in 122 newly presenting black Tanzanian diabetic patients in Dar es Salaam. ICA were found in three (8.6%) IDDM patients and five (6.8%) insulin-requiring NIDDM patients; six of the eight were also CF-ICA positive. Altogether 22% of patients showed one or more positive autoantibody result but there was no clustering of response, and no association of ICA with other antibodies except for two NIDDM subjects who showed one other positive result. There were no differences between insulin-requiring (IDDM) and NIDDM subjects or between younger (less than 30 years) and older patients. We conclude that there is no major association between diabetes and islet cell antibodies in black Tanzanians.