Objective To investigate the reasons of higher result of CK-MB than the total CK with the immune suppression method for deteting serum CK-MB and solution methods.Methods Selected 68 cases of inpatients with myocardial infarc-tion from Department of Cardiology,32 cases of malignant tumor from Internal Medicine-Oncology,including 8 cases of liver cancer,6 cases of lung cancer,6 cases of gastric cancer,5 cases of neuroblastoma,4 cases of breast cancer and 3 cases of o-varian cancer and 16 cases of cirrhosis from Department of Gastroenterology,and at the same time,selected 100 cases of healthy persons as control group from Out-patient Health Examination Center of Shaanxi Provincial People’s Hospital.Used Roche MODUALR automatic biochemical analyzer to detected the activity of serum CK-MB with the immune suppression method and the activity of total CK with the enzyme coupling rate method.Results In 68 cases of inpatients with myocardial infarction,the activity of serum CK-MB of 2 1 cases were individually increased,the activity of total CK of 3 9 cases were in-creased,and the two indexes of 30 cases were increased in the same period.In 32 cases of inpatients with malignant tumor, the activity of serum CK-MB of 1 1 cases were individually increased,the activity of total CK of 3 cases were increased and the two indexes of 3 cases were also increased.The activity of serum CK-MB of 6 cases were individually increased in 1 6 ca-ses of cirrhosis.Conclusion The immune inhibition assay for the detection of CK-MB as the diagnosis index of myocardial infarction had certain defects,and the higher activity of CK-MB could be highly associated with some severe inflammation, malignant tumor.