In patients with adult polycystic kidney disease (APKD) infected cysts are difficult to localize with current radiographic techniques, especially those dependent on renal function. Indium-111 leukocyte (In-WBC) imaging is both highly sensitive and effective in detecting and localizing abscesses in patients with renal failure. We report on a patient with APKD and sepsis in whom computed tomography, ultrasound, and physical examination failed to locate the renal abscess, which was found by In-WBC scanning.