Carcinoma of the pancreas is an exceptionally difficult lesion to diagnose. Even at laparotomy, pancreatitis and this malignant neoplasm may appear indistinguishable, both by inspection and palpation. Conventional biopsy itself, by the thick Vim-Silverman needle or wedge section, may be associated with morbidity or mortality. However, thin-needle aspiration biopsy with an 18-gauge bore has proved a safe, accurate diagnostic method. Twenty-one such aspiration biopsies were taken during laparotomy; from 12 patients with carcinoma, 11 revealed definite tumor cells. This form of biopsy was utilized for frozen-section diagnosis, and one Whipple operation successfully followed this procedure.