Background : Although elevated serum fibrinogen are known to be associated with coronary atherosclerosis and acute myocardial infarction (AMI) with thrombus formation, the association between the elevated level of fibrinogen and coronary spasm remains to be elucidated. The purpose of this study is to determine whether the elevation of serum fibrinogen levels is a risk factor for coronary spasm and also for the development of AMI in patients with coronary vasospasm. Methods : Consecutive 231 patients documented coronary vasospasm by ergonovine provocation test, but without a significant stenosis (>50%) were devided two groups, angina pectoris patients (group I; n=202, 49.5짹11.1 years) and AMI patients (group II; n=29, 47.4짹11.2 years). And, AMI with significant stenosis (>50%) patients matched another control group (group III; n=84, 61.2짹11.8 years). Results : Baseline clinical characteristics were no differ among the group I and II. But, group III patients were significantly more than the age of the group I and II patients. The incidence of hypertension, diabetes mellitus and smoking history were lower in the group I than in group III (diabetes, 7.9 vs 13.8 vs 29.8%; hypertension, 19.8 vs 24.1 vs 41.7%; smoking 48 vs 48.3 vs 61.9%; respectively, p<0.01) but, no differ among the group II and III. The serum Lp(a), fibrinogen, hsCRP, apolipoprotein B/A1 ratio were measured in total patients. The hsCRP, fibrinogen level were higher in group II and III (group II; 1.88짹2.9 mg/dl, 317.5짹51.2 mg/dl, and group III; 2.92짹3.9 mg/dl, 326.8짹107.7 mg/dl) than in group I (0.68짹1.5 mg/dl, 263.2짹70.3 mg/dl) (respectively, p<0.001, p<0.001). The multivariate analysis confirmed that higher fibrinogen level is an independent determinant for AMI in vasospastic patients (odds ratio, 8.35; 95%, confidence interval, 1.94 to 30.0). In these patients, Fibrinogen and hsCRP were showed good correlation (r=0.472, p<0.001). Conclusion : Elevated fibrinogen level was associated with AMI patients with coronary vasospasm. This results suggested that fibrinogen may play an important role in the genesis of thrombotic coronary occlusion and the occurrence of AMI subsequent to coronary spasm.