We examined the effects of fibroblast growth factors (FGFs) on rat pancreatic acinar cells in primary culture. Both basic and acidic FGF stimulated [3H]thymidine incorporation in a dose-dependent fashion. Maximum effects of 6-7 fold over control were seen with 1 nM bFGF or 100 nM aFGF. These data indicate that FGFs are potent stimulants of rat pancreatic acinar cell DNA synthesis. Therefore, FGFs may play an important role in long term regulation of the exocrine pancreas in vivo. We also examined the interaction of bFGF with the pancreatic secretogogues CCK and carbachol. Effects of CCK, which is itself an acinar cell trophic factor, were additive with those of bFGF. In contrast, carbachol, which has no growth stimulatory effect, did not affect bFGF mediated stimulation of DNA synthesis. These data suggest that the mechanisms involved in acinar cell growth regulation are independent from those involved in secretion.