A 58 year-old man with end-stage renal disease who had received a cadaveric renal transplant presented with persistent hypertension and hypokalemia. Allograft renal artery stenosis, rejection, and cyclosporine effects were excluded. Hypokalemia persisted despite potassium supplementation and antihypertensive medications with hyperkalemic effects. The biochemical findings of primary hyperaldosteronism with a normal adrenal anatomy imaged by magnetic resonance imaging (MRI) necessitated adrenal vein sampling to lateralize a left adrenal adenoma. His hypokalemia was cured by the removal of the adenoma, and his blood pressure (BP) control was easily achieved with a less complex regimen of antihypertensives. We suggest that the concomitant existence of resistant hypokalemia and posttransplantation hypertension, especially in the cyclosporine era, should stimulate a search for hyperaldosteronism; once transplant renal artery stenosis has been excluded, the patient should be investigated for primary hyperaldosteronism. When imaging studies fail to show adrenal pathology, adrenal vein sampling will likely do so.