Objectives To study the status of fibrinolytic inhibition in patients of acutecoronary syndrome(ACS) complicated with type Ⅱ di-abetes mellitus (NIDDM) and to evaluate the effectof fibrinolytic inhibition to the clinical prognosis.Methods Type Ⅱ diabetes mellitus was defined byADA 1997/WHO 1998 criteria. The subjects weredivided into treatment groups that included 39 patientsof ACS with 20 cases of acute myocardiac infarction(AMI), 36 patients of ACS + NIDOM with 20 cases ofAMI. Twenty cases of healthy people were randomizedto control group. The plasma level of tissue type plas-minogen activator (t- PA), plasminogen activator in-hibitor type - 1 (PAl - 1 ) and plasma D - dimer weredetected by using elisa technique. The index of statuein fibrinolysis was detected with the plasma level of D-dimer and the rate of PAI- 1/D- dimer in per-centage. This index was used to evaluate the fibri-nolytic inhibition and the clinical outcome in all thepatients with AMI in treatment groups. The clinicaloutcome in patients with AMI consisted of the rate ofreperfusion, the incidences of re- infarction, severi-ohs arrhythmia, pump failure and death in the earlyperiod of AMI. Results The plasma level of PAI - 1and D -dimer was higher in the two treatment groupsthan that in the control group ( P ＜ 0. 01). The plas-ma level of PAI- 1 significantly higher in ACS +NIDDM patients than that in ACS (P ＜ 0.05), butthe plasma level of D- dimer raised from basic levelwas significantly lower in ACS + NIDDM than that inACS ( P ＜ 0. 05) . The rate of PAI - 1/D - dimer inpercentage was significantly higher in ACS + NIDDMthan that in ACS or in control group ( P ＜ 0. 01 ). ForAMI patients in two treatment groups, the rate ofreperfusion after the thrombolytic therapy was signifi-cantly lower in ACS + NIDDM than that in ACS( P ＜0. 01) . The rate of incidences in pump failure wassignificantly higher in ACS + NIDDM than that in ACStoo ( P ＜ 0.05). The morbidity of severious arrhyth-mia, re- infarction and the mortality were also higherin ACS + NIDDM; however the difference was not sig-nificant ( P ＜ 0.05) . Conclusions The plasmalevel of D - dimer combined with the rate of PAI - 1 /D- dimer in percentage could be used to be the evidenceand the index to evaluate the status of fibrinolytic in-hibition in patients of ACS + NIDDM, and could beused to evaluate the effect of the fibrinolytic inhibitionto the outcome of treatment and clinical prognosis inACS patient.