This study was undertaken to investigate the prevalence of diabetes complications and level of glycaemic and blood pressure control in Black African patients at the primary care level in the public sector Cape Town, South Africa. A stratified random sample of 300 patients attending the three largest ambulatory diabetes clinics in community health centres in Black African residential areas of Cape Town (100 patients from each) during the last 6 months of 1992 was selected. Each patient had a clinical examination, interview, and 1 year retrospective record review. Eighty-one per cent of the sampled patients were reviewed, 90% were non-insulin-dependent (NIDDM) and 10% were treated with insulin. The mean duration of diabetes was 8 (range 0-28) years. Acceptable glycaemic control was present in 49.4% (95% Confidence Intervals 45.6-53.5) of patients while 38.5% (CI 24.8-52.2) of hypertensive patients had acceptable blood pressure control. The prevalence of any grade of retinopathy was 55.4% (CI 48.90-62.9), proliferative and preproliferative retinopathy 15.6% (CI 8.5-22.8), cataracts 7.9% (CI 4.4-11.4), peripheral neuropathy 27.6% (CI 15.2-39.4), absent foot pulses 8.2% (CI 5.2-12.6), amputations 1.4% (CI 0.4-2.4), persistent proteinuria 5.3% (CI 2.5-8.1) and an elevated albumin-creatinine ratio 36.7% (CI 29.0-44.4). The complications were not documented in the clinic records of the preceding year with the exception of 1 patient with absent foot pulses and the 12 patients with proteinuria. The high prevalence of suboptimal glycaemic and blood pressure control as well as complications of diabetes, largely unrecorded in the preceding years' clinic notes, demonstrates the deficiency of and need for preventative diabetes care at the primary care level. The design, institution, and evaluation of effective intervention programmes are a priority to improve the quality of care provided and the health of diabetic patients.