In the past four years percutaneous ultrasonically guided fine needle aspiration biopsies of space occupying lesions of the abdomen and retroperitoneum wee performed on 180 patients. There were 71 aspirations of cystic and 169 aspirations of solid lesions. Amongst the latter pancreas was first with 67 followed by the liver with 58, the kidney with 31 and other organs of the abdomen with 13 aspirations. No diagnostic material was obtained in 27 percent of aspirations of the pancreas and in 18 percent of kidney aspirations. The cytological diagnoses were right positive in 88 percent and false negative in 12 percent. There was no false positive result. 5 pseudocysts of the pancreas wee aspirated therapeutically, in one case 8 times subsequently. The only complication of all aspirations was a pancreatitis which healed under conservative treatment. There were 4 therapeutic aspirations of kidney cysts. 860 ml urine was drained from the largest cyst. We conclude that percutaneous ultrasonically guided fine needle aspiration biopsy is an easy, safe and painless method of diagnosis of space occupying lesions of the abdomen and retroperitoneum. The same applies to therapeutic aspirations of cysts of the pancreas and kidney.