Serial changes of serum IgE, IgG, eosinophils were observed in 25 patients with acute myocaridial infarction and 20 ischemic heart disease without evidence of acute myocardial infarction and evaluated in terms of several parameters and its clinical significance. The results observed were as follows : 1) Serum IgE levels were propgressively elevated from the first hospital day(259+/-3IU/ml) up to peak level of the fifth hospital day(415+/-2IU/ml) and progressively lowered and returned to almost same level as the first hospital day on the twenty first hospital day. On the other hand control group showed significantly lower IgE levels throughout all hospital day and also did not showed serial change. 2) In the patient group with the initial serum IgE level above 200IU/m; showed significantly lower level of serum SGOT, CPK level than the group of below 200IU/ml group. This suggests the initial serum IgE level might have some correlation of the extent of myocardial necrosis. 3) In patients of acute myocardial infarction, ejection fraction was checked at discharge. Initial serum IgE level above 200IU/ml group showed significantly higher ejection fraction than below 200IU/ml group(59.4+/-13.5% vs 38.4+/-13.7%). 4) Serum IgE was checked concomittantly with serum IgE. It showed slightly decreasing tendency at third hospital day but not statistically significant. Eosinophil changed similar pattern as serum IgE but it was also not statistically significant. In conclusion, serial checking of serum IgE level in patient of acute myocardial infarction may give some help in prediction the clinical course and prognosis.