19% of 1490 abdominal sonograms from 1192 patients led to findings which were not related to the original purpose of the sonogram or to the actual disease, and of which neither the treating physician nor the patient were aware. The most frequent findings were those in liver, kidneys and gallbladder. The majority of ultrasonographically detected lesions were benign; tumour diseases were suspected only in 26 cases. The incidence of such findings increased with the patients' age. The positive, predictive value of the findings was around 90%. In 20% of the patients with unexpected findings, further diagnostic measures were taken; therapeutic consequences were recorded in only twelve cases. Further measures were recommended in 20% of the patients, a majority of which had pancreatic and vascular abnormalities. Because such findings may considerably facilitate the diagnosis of subsequent complaints, all accessible organs should be examined during abdominal ultrasonography.