Ganglioneuromas are localized tumors derived from neural crest tissues. Characteristically, they originate in the posterior mediastinum. Pure adrenal gangliomas are extremely rare.A left adrenal mass with the size of 68mm×50mm×86mm on magnetic resonance imaging was documented in a 53-year-old female patient. Endocrine tests revealed a non-functioning adrenal mass. The actual size of the mass was macroscopically measured to be 16cm×8.5cm×6cm after the surgery. Histopathological examination indicated ganglioneuroma.Most adrenal ganglioneuromas can incorrectly be diagnosed as other adrenal tumors, since they are rare neurogenic benign tumors with no specific imaging properties. They have a slow growth pattern and usually asymptomatic. Our case represents a huge adrenal ganglioneuroma in a female patient with nondiagnostic flank pain. Radiological imaging showed a large adrenal mass with no differentiation from other adrenal tumors. Endocrine evaluation should be performed for such adrenal masses. Since our case had a relatively large size, open surgery was preferred. Pathology revealed the definitive diagnosis.This case suggests that ganglioneuromas can wrongly be diagnosed as other adrenal tumors. It is significant that a proper differential diagnosis should be performed by using hormonal and imaging techniques. Nevertheless, pathological examination is usually required for definitive diagnosis.