Afro-Caribbeans are the second largest ethnic minority in the UK and are concentrated in some inner London areas where they comprise over 12% of the population. Standardized mortality ratios for stroke are relatively high among the Afro-Caribbeans, for whom the control of high blood pressure is thus of particular significance. Semi-structured interviews were conducted with matched groups of 'white' and Afro-Caribbean hypertensive patients attending 15 general practices in an inner London area to examine their beliefs and practices regarding the prescribed drugs. Adherence was high among 'white' patients, but less than half the Afro-Caribbeans took the drugs regularly as prescribed with many having poorly controlled blood pressures. Non-adherence was influenced by traditional cultural beliefs and practices which often strengthened concerns about the long-term harmful effects of drugs and provided an alternative resource in terms of herbal remedies. There was also evidence of a cultural gulf and lack of communication between Afro-Caribbean patients and their general practitioners, thus reducing the effectiveness of this preventive strategy.