The relation between cardiovascular diseases and serum immunoglobulin E (Ig E) levels has been investigated by different authors. Serum Ig E may play a direct role in The pathogenesis of cardiovascular diseases, or it may only be a marker formed during pathological mechanisms. In this study, we determined serum Ig E levels of patients with unstable angina pectoris and myocardial infarction. Serum Ig E levels of 30 patients with acute myocardial infarction and 20 patients with unstable angina pectoris were deter-mined within the first 6 and 12th hours and on 2nd, 4th, 8th days of the hospitalization and these levels were compared with the serum Ig E levels of normal subjects reserved as control group. As a result, at all measurement hours, serum Ig E levels of acute myocardial infraction group were found to be approximately fourfold increased when compared to those of unstable angina pectoris and those of control group (p<0.001). In the acute myocardial infarction group, no significant differences could he found between the levels of the first 6th and 12th hours nod on the 2nd, 4th, 8th days. Also, no statistically significant difference was found between the serum Ig E levels of unstable angina pectoris and those of control group.