Objective: To retrospectively investigate influencing factors for high-burden thrombus formation (HBTF) in the acute myocardial infarction related right coronary artery(RCA).  Population and Methods: A total of 87 consecutive patients with AMI related to RCA established through CAG procdeure in Da lian medical university affiliated No.1 Hospital from 2004 to 2005. Classified them into 2 group: the massive thrombus group [n=36 patients, TIMI  3 cm)]; the non-massive thrombus group [n=51 patients, TIMI >3 accompanied with thrombus process (linear intraluminal radiolucency < 3 cm ) or only stegnosis .The variables of age、gender、elapsed time、risk factors、complications and lab examination [including white blood cell count (WBC count)、activated partial thromboplastin time (APTT)、prothrombin time (PT )、Fibrinogen ] were reviewed and underwent logistic regression analysis.  Results :The elapsed time was significantly longer in the massive thrombus group (13.95±5.00 hr ) than that in the on-massive thrombus group (7.4±4.50 hr, p<0.05). Patients in the massive thrombus group had a greater incidence of hypertension than the non-massive thrombus group (p<0.05). But the incidence of diabetes in the non-massive thrombus group was greater than that in the massive thrombus group (p<0.05). WBC count in the massive thrombus group was greater value than that in the non-massive thrombus group. Fibrinogen、CKMB and TnT were in the