OBJECTIVE. To observe the therapeutic effect and safety of brief - duration intravenous infusion of SK in patients with AMI. METHODS. One hundred and twenty patients with AMI were treated by brief - duration intravenous infusion of SK (BEHRING), 1.5 million units within 30 minutes. All patients were divided into two groups randomly. One group were given dexamethasone 2~5 mg and the other group were not. RESULTS. 1. The reperfusion rate was 75.0% and the total 5-week mortality rate was 5.0%. The rate of bleeding was 8.3%. The reperfusion rate of the patients who received thrombolysis less than 6 hours after the onset of symptoms was much higher than that of more than 6 hours (P < 0.01). 2. The rate of occurrence of allergic reactions revealed no significant differences between the two groups (P > 0.05). 3. There were also no significant differences in the reperfusion rate and the rate of occurrence of side effects between ≤ 65 yrs group and > 65 yrs group (P > 0.05). The rate of reperfusion arrhythmia was 38.3%. CONCLUSIONS. 1. Brief-duration intravenous infusion of SK in patients with AMI appearetd to be safe and effective, and suitable to Chinese. It is necessary to advocate prehospital thrombolysis while transporting to hospital or in emergency room. 2. There is no clear conclusion wether dexamethasone may prevent allergic reactions caused by SK. 3. It is safe to administer intravenous infusion of SK to patients who are over 65 yrs old, but the patients' general conditions should be considered carefully.