The diagnosis of adrenal cysts is becoming increasingly more common with the widespread use of diagnostic imaging modalities. Most adrenal cysts are asymptomatic and less than 10 cm in diameter when discovered incidentally. Symptoms appear when adrenal cysts enlarge sufficiently to cause pain and gastrointestinal disturbances or become palpable. In this report, we present a case of a giant 45-cm right adrenal cyst manifesting as painless abdominal distention in a 23-year-old female. This case appears to be one of the largest adrenal cysts reported to date. The classification and management of adrenal cystic lesions is reviewed.