This work was carried out on 24 patients suffering from acute chest pain suspicious of acute myocardial infarction ( AMI ) and 10 well matched normal controls . Patients and controls had undergone electro- cardiographic monitoring ( ECG ) , determination of serum creatine phosphokinace ( CPK ) and serum myoglobin by turbidimetric immunoassay. Out of these 24 patients 9 proved to have unstable angina and 15 had AM! . Eleven patients were admitted within 24 hours and 13 within 6 hours from the onset of chest pain. Out of these 13 patients only 9 had AM! . Sensitivity of myoglobin , CPK and ECG in all patients with AM! was 86.8% , 60% and 66.6% respectively. The sensitivity of myoglobin and CPK in AMI patients admitted within 6 hours was 88.8% and 33.33% , respectively . The specificity for myoglobin , CPK and ECG in all AMI patients was 100% .Therefore serum myzolobin assay by immunoturbidmetric method can be considered as a sensitive and specific test to diagnose AMI in the first few hours and also to identify those patients without definite ECG changes.