Study of 81 cases. Fine Needle Aspiration Biopsy (FNAB) was performed under computerized thomography scan (CT) in 81 patients with documented pancreatic mass (54 with neoplasia and 27 with chronic pancreatitis). This procedure, when associated to the immediate cytological evaluation of the adequacy of the smears, permits to obtain 100% in sensibility, specificity and predictive value of positive cases. These results and the study of the literature confirm CT-guided FNAB of the pancreas as the procedure of choice to resolve problems of differential diagnosis in pancreatic masses.