Adrenal cysts are an uncommon finding, in most cases unexpectedly discovered in the evaluation of nonspecific abdominal pain or at autopsy. Cystic adrenal masses can be classified into neoplastic and non-neoplastic aetiologies. The distinction between malignant and benign adrenal cysts can still be difficult. Cysts of neoplastic aetiology occur as a result of necrosis and cystic degeneration within both benign and malignant tumours. Non-neoplastic cysts have been conventionally divided into four categories: endothelial (45%), haemorrhagic or pseudocystic (39%), epithelial (9%) and parasitic (7%). Small adrenal cysts are clinically silent, while cysts of large size can cause displacement and compression of adjacent organs. The radiological aim is to detect the adrenal mass and CT is regarded as the best method available for this detection, although a differentiation between benign and malignant tumours can be difficult. Here we report our experience in nine patients with adrenal cysts. Abdominal pain was the dominant sign, two patients were hypertensive, one presented a palpable mass at abdominal examination and another presented oligomenorrhea with hypertrichosis, in five patients the adrenal mass was discovered unexpectedly during radiologic examination. All cysts in our patients were unilateral. All patients were examined by ultrasound and CT, one by RM, three by 75Se-Seleniumcholesterol cortical scintigraphy and two by 131I-MIBG medullary scintigraphy. In three patients a percutaneous aspiration of the cyst was performed via a posterior approach with CT or US guidance. This approach has been used for diagnostic and therapeutic purposes. Examination of aspirated cyst fluid for steroid hormones showed markedly elevated cortisol levels compared with normal plasma cortisol levels in one patient.(ABSTRACT TRUNCATED AT 250 WORDS)