Hypertension prevalence, treatment status and factors relating to high blood pressure were determined in an urban black community of the Cape Peninsula, South Africa. A study population of 986 subjects aged 15-64 years was randomly selected. Blood pressure, height, weight and serum cholesterol levels were measured, while demographic information, personal and family history relating to hypertension and attendance of health services were determined by questionnaire. Overall 9.2% of males and 12.9% of females were hypertensive according to WHO criteria. Blood pressures between 160/95 and 140/90 mmHg were found in 10% of males and 10.5% of females. The treatment status of hypertensives showed that 24.3% had a blood pressure below 160/95 mmHg, and 16% below 140/90 mmHg. Hypertensives used more alcohol and were more overweight than normotensives. Multiple logistic regression revealed that hypertension was independently related to age, being overweight and more urbanised. The degree of urbanisation also predicted to what extent hypertension prevalence increases with age. This black population had low hypertension rates compared with other similar groups in South Africa. These data suggest that as rural blacks increasingly undergo urbanisation, hypertension prevalence increases. Necessary diagnostic and treatment regimens and hypertension services are not yet in place in the South African health services, and need to be established.