Aim. Immunohistochemical determination of cell proliferation and apoptosis processes in PanIN in ductal adenocarcinoma (DA) and chronic pancreatitis (CP). Materials and methods. Comprehensive histological, histochemical and immunohistochemical (IHC) study was carried out on the biopsy-postoperative material of 36 patients with CP with severe fibrosis of the pancreas, as well as 80 patients with DA. Results. Reliable differences were shown in evidence of these processes in the zones of pancreatic intraepithelial neoplasia (PanIN) in carcinoma and pancreatitis, and also depending on the stage of PanIN. Thus, in chronic pancreatitis and pancreatic carcinoma cell proliferation average index in PanIN-1 was 0,75 +/- 0,46 and 0,96 +/- 0,42 points respectively, and in PanIN-2-1,39 +/- 0,64 and 2,2 +/- 0,8 points respectively. It testifies that level of proliferation and apoptosis processes in PanIN in patients with pancreatic ductal adenocarcinoma is higher, than in patients with chronic pancreatitis.