Abstract: Soluble interleukin - 2 receptor (sIL - 2R) in 19 patients with proven unstable anginawas measured in plasma by ELISA- The result was compared with those of 21 with stable allgina and 16healthy subjects. The level of sIL - 2R in patients with unstable angina was higher than in patients withstable angina and control subjects, and it decreased significantly after angina was controled. This resultsuggests that immune system - mediated inflammatory might play an important role in the pathoplysiol0gyof unstable angina- The detection to serum sIL - 2R could help for diagnosis of unstable angina.