We describe a case of primary aldosteronism due to an aldosterone producing adenoma with high and non-suppressible plasma renin activity (PRA). She had suppressed PRA at initial diagnosis. This rose above the reference range for normal individuals over a period of 7 years with untreated hypertension. We discuss the possible pathophysiological causes of a rise in PRA in this clinical setting and suggest that underlying arteriolar disease due to prolonged hypertension may be the cause of increased and non-suppressible PRA in primary aldosteronism.