Activated lymphocytes can release a soluble form of interleukin-2 receptor (sIL-2R) and abnormally high serum levels of sIL-2R have been reported in patients with advanced solid tumours and in those with chronic disease. We determined serum sIL-2R concentrations in 34 patients with chronic pancreatitis (8 in painful relapse), in 40 with pancreatic tumours in various stages, and in 40 healthy subjects as controls. Patients with pancreatic cancer and those with chronic pancreatitis had significantly higher serum concentrations of sIL-2R than healthy subjects (p < 0.001). In patients with Stage II pancreatic cancer, serum levels of soluble receptors were similar to those in patients with Stage III tumours, and these concentrations were significantly higher than in patients with resectable cancer (p < 0.01 and p < 0.05, respectively). In chronic pancreatitis patients, those studied during painful relapse of the disease had higher serum concentrations of sIL-2R than those studied during clinical remission (p < 0.05). The results of our study suggest an activation of the cellular immune system in pancreatic cancer and in chronic pancreatitis.