Although chronic pancreatitis microscopically surrounding pancreatic carcinoma is common, cancer developing in chronic pancreatitis has rarely been shown. We present four such cases seen between 1983 and 1988. All were male, mean age 56.7 years, and all had had previous surgery for complications of chronic pancreatitis (two a pancreatectomy, two a bypass). Chronic pancreatitis was caused by alcohol in three cases, and calcification was present in three. The delay between chronic pancreatitis and pancreatic carcinoma was 2 to 10 years, and in all, pancreatic carcinoma was at an advanced state, with post-surgical survival of 1.5 to 6 months. CA 19.9 level was very high in the three cases in which it was measured. That pancreatic carcinoma is more frequent in populations with chronic pancreatitis, occurring later in life than pancreatic carcinoma that has no coexisting chronic pancreatitis (sixth decade vs. fifth), often with intermediate histology, argues for chronic pancreatitis degenerating into pancreatic carcinoma rather than for a common toxic etiology. Pancreatic carcinoma occurs particularly in calcified chronic pancreatitis, and diagnosis is frequently quite late, due to the non-specificity of symptoms vs. chronic pancreatitis. Delay of appearance is variable, and previous surgery and histological examination excludes obvious coexisting pancreatic carcinoma. Aggressive surgery appears justified if needed for chronic pancreatitis, and chronic pancreatitis should be carefully followed, probably by serial CA 19.9 determinations and guided percutaneous fine needle biopsies when elevated, or when new symptoms are present in chronic pancreatitis.