Two middle-aged men were referred for control of severe hypertension, presumed to be 'essential'. Late-onset enuresis, a small palpable bladder, and slight prostatic enlargement were elicited in one patient; history and examination were unremarkable in the other patient, apart from moderate prostatic enlargement. Intravenous urography revealed massive bilateral hydronephrosis with hydroureters in both patients. Surgical relief of retention was associated with post-obstructive diuresis and normalization of blood pressure, although recurrence of hypertension occurred later in one patient. These patients suffered from high pressure chronic retention, a syndrome characterized by impairment of renal function and hypertension. Surgical relief of retention was accompanied by prompt correction of hypertension, and gradual, sustained recovery of renal function.