Altered activity of the sodium-hydrogen exchanger (NHE) has been implicated in the development of hypertension. The aim of the study was to determine if the indices of urinary acid-base excretion (as markers of the NHE activity) are increased in hypertensives compared to normotensive black Africans. Sixty black African subjects (30 untreated hypertensives and 30 normotensives) were recruited for the study. All subjects collected timed 24 hour urine for quantification of the indices of acid excretion. There was no difference in all the measures of acid excretion between hypertensives and normotensive subjects: p=0.384 for urine pH, p=0.442 for urine ammonium, p=0.279 for urine titratable acidity and p=0.304 for total acid excretion. This suggests that there is no difference in urinary acid excretion between black hypertensives and normotensives and that the NHE may not be implicated in the genesis of hypertension in blacks.