black South Africans

Beta-blockers are effective hypotensive agents in Caucasians. In a double-blind cross-over trial on 18 hypertensive Jamaicans, however, Humphreys and Delvin found no significant difference between propranolol and an inert placebo.2 This was not confirmed by Grell in an open study of the drug.3 I reported control of blood pressure with propranolol in eight out of 12 Indians and only four out of 13 black hypertensive patients.4 The fall in blood pressure in the Indians as compared with the blacks was statistically significant (p <0 002). Evidence suggests that most blacks with hypertension have low plasma renin activities.5 Diuretics such as chlorthalidone increase plasma renin activity. Hence I decided to study the effect of atenolol 100 mg once daily alone and in association with chlorthalidone 25 mg once daily and to compare them with