Twenty-seven male and female black Zimbabweans hypertensive patients were matched by age and sex and compared to 27 normotensive subjects. All subjects were examined after dietary sodium depletion, followed by sodium loading. In addition to renin status and salt-sensitivity, urine aldosterone, renal prostaglandins, plasma atrial natriuretic peptide (ANP) and plasma endothelin were assessed. The following ethnic characteristics for Zimbabwean essential hypertensive patients were found: increased prevalence of salt-sensitive hypertension (66 pc); hyporesponsive renin-angiotensin system after contraction of circulating plasma volume; higher prevalence of low-renin hypertension (59 pc); suppressed renal prostaglandins, especially in low-renin hypertensives, suggesting suppression or deficit of renal kallikrein-kinin system; increased levels of ANP in low-renin hypertensive patients. Plasma endothelin was comparably increased in both normal- and low-renin hypertensive patients.