A retrospective study was performed on 54 patients diagnosed as having adrenocortical carcinoma during 1974-1983. The initial symptoms were often diffuse: abdominal pain, weight loss, or fever, and more than 60% of the patients showed no evidence of overproduction of hormone. The median tumor diameter was 13 cm and almost half of the tumors had metastasized at diagnosis. A radical tumor resection could be performed in less than 50% of the patients, and at histopathological re-examination some tumors were not conclusively verified as malignant. Capsular invasion, nuclear pleomorphism and mitoses were found more commonly in patients who succumbed to the disease. Seven of 29 patients treated with chemotherapy showed an objective response and two of them are still alive and free of disease. The overall 5-year-survival rate was 19%, compared with 45% for patients with radically resected tumors. Patients with no biochemical signs of overproduction of adrenocortical hormone appeared to have a better prognosis than those with hormone excess. Together with increased use of ultrasound and computed tomography, a urinary steroid profile might hopefully contribute to earlier discovery of these often clinically silent tumors. However, it remains to be determined whether these diagnostic improvements, together with more aggressive surgery and adrenolytic chemotherapy, can improve the poor prognosis.