After an episode of acute pancreatitis (AP) in humans, the pancreas exhibits varying degrees of fibrosis, acinar cell regeneration, and the formation of tubular complexes. The mechanisms underlying these changes are unknown. By using Northern blot analysis and immunohistochemistry, we assessed the expression and distribution of fibroblast growth factors (FGFs) and their receptor in human pancreatic tissues obtained from patients with AP. By comparison with the normal pancreas, acidic FGF (aFGF) and FGF-receptor 1 (FGFR-1, flg), mRNA levels were significantly decreased in human pancreatic tissues, which were obtained approximately 8 days after onset of AP. In the normal pancreas, acidic FGF, basic FGF, and FGFR-1 immunoreactivity was present at low to moderate levels in a heterogeneous pattern in the cytoplasm of acinar and ductal cells. Two patterns of immunoreactivity were observed in the AP group. In regions that have undergone necrosis, there was complete loss of aFGF, bFGF, and FGFR-1 immunostaining. In contrast, in the regenerating areas, aFGF and bFGF were readily evident in exocrine-type cells, in association with a marked increase in FGFR-1 immunoreactivity. These findings indicate that FGF/receptor expression is altered after AP, and raise the possibility that FGFs may be involved in the process of pancreatic exocrine regeneration during recovery from AP.