Objectives: In Oman, many hypertensive patients with a family history of the disease respond to treatment with spironolactone, a mineralocorticoid receptor (MC-R) blocking agent thus suggesting a high prevalence of mineralocorticoid (MC) induced disease. The aim of this study was to document the prevalence of MC induced disease in patients with a positive family history of hypertension (HTN). Methods: Serum calcium, potassium, creatinine, aldosterone and renin levels were measured under standard conditions in all patients together with an abdominal ultrasound scan and an adrenal computed tomography (CT) scan in four patients. Results: In this small study, we show that 18 of the 27 patients (66%) had undetectable (suppressed) renin levels with usually normal aldosterone values (14 patients) and respond to treatment with spironoactone. Conclusion: We suggest that MC induced hypertension is likely to be common in the Middle East. In evolutionary terms, this makes sense as the ability to conserve salt in hot climates might be expected to confer a definite survival advantage.