Fine-needle aspiration biopsy (FNB) was performed with ultrasound guidance in 79 patients in whom sonography had revealed a mass suggesting pancreatic malignancy. The final diagnosis (surgery, autopsy and clinical course) in 69 of these 79 patients was a malignancy closely related to the pancreas while in the remaining 10 patients benign disease was confirmed. A correct diagnosis of malignancy was attained by FNB in 59 of the 69 patients with a malignant tumour while in 10 it failed to confirm the diagnosis. FNB yielded a true negative result in 10 patients with benign disease. The accuracy of sonographically guided FNB in the present investigation was 87 per cent. Ultrasound-guided fine-needle biopsy is considered the method of choice for further evaluation of pancreatic masses.