In order to investigate the influences of taurine on thrombolysis serum endothelin (ET) concentration was determined in patients with acute myocardial infarcation (AMI) without urokinase (UK) treatment (group 1) and after treatment with UK (group 2) or UK combined with taurine (group 3). In a rat model with abdominal aorta thrombosed by FeCl3, the changes of serum ET, malodialdehyde (MDA) and intravascular thrombosis were observed in three groups same as in patients. The results were as follows: (1) Serum ET levels of group 1 patients at early phase of onset (6 hours) were significantly higher than those of the controls (47.3 +/- 6.3 ng/L vs 20.4 +/- 9.7 ng/L, P < 0.001). After two days serum ET decreased to normal level. Serum ET levels were significantly higher from 6 to 10 hours after the onset of AMI in group 2 than in group 1 (70.8 +/- 6.6 ng/L vs 56.9 +/- 8.6 ng/L, P < 0.01, at 8 hours). Serum ET levels were significantly lower from 8 hours to a week after onset of AMI in group 3 than in group 2 (33.3 +/- 8.2 ng/L vs 70.8 +/- 6.6 ng/L, P < 0.01, at 8 hours). (2) In the rat model with thrombosis of abdominal aorta, the changes of serum ET were similar to those of AMI patients. In addition serum MDA levels were significantly decreased (20.85 +/- 3.05 mumol/L vs 25.18 +/- 3.53 mumol/L after combined treatment with UK and taurine, P < 0.05). The ratio of cross area of vascular lumen and thrombus was lower after treatment with combination of UK and taurine than treatment with UK alone (0.4650 +/- 0.0928 vs 0.6176 +/- 0.1179, P < 0.05), the results suggested that taurine can decrease significantly serum ET levels, potentiate UK-induced vascular recanlization and reduce ischemia reperfusion injury. Taurine might be useful clinically as an adjunct of thrombolytic therapy.