A well-differentiated ductal adenocarcinoma of the Syrian golden hamster induced by N-nitrosobis(2-oxopropyl)amine was transplantable to both nude mice and inbred Syrian hamsters. The tumor grew rapidly in the nude mouse (12-fold increase in size at 45 days) in contrast to its growth in hamster (3-fold increase in size at 45 days). A curious finding associated with the slow-growing tumor in the hamster was an intense infiltration of the neoplasm by polymorphonuclear leukocytes unattended by either necrosis or infection. The neoplasm produced mucin and rapidly and specifically bound 125I-labeled secretin, although the degree of nonspecific binding (40.5%) was higher than that of control hamster pancreas (23%). Unstimulated adenyl cyclase activity (pmol cyclic adenosine 3':5'-monophosphate per mg protein) of the neoplasm was significantly higher [3.76 +/- 0.55 (S.E.)] than that of unstimulated normal hamster pancreas (1.03 +/- 0.44). Secretin did not significantly change the level of cyclic adenosine 3':5'-monophosphate (3.3 +/- 0.56) from the unstimulated level in the neoplasm, in contrast to its effect on normal pancreas where the level was increased 3-fold (3.1 +/- 0.75).