Aim The synthesis and release of endothelin (ET)in patients with coronary heart disease undergary percutaneous transluminal coronary angioplasty has not been concluded. This study examined the porsible association between endothelin and coronary atherosclerosis and evaluated the synthesis and release of endothelin in the presence of various stimuli that occur during percutaneous transluminal coronary angioplasty.Methods The plasma from femoral artery blood and urinary concentrations of endothelin immunoreactivity in 15 patients and 10 healthy control subjects were measured before and after percutaneous transluminal coronary angioplasty.Results The basic plasma and urinary ET-1 level was higher than the control subjects (<0.01).Changes were not detected in peripheral plasma concentrations of ET-1 within 24 h (p<0. 05), but found increase in urinang ET-l levels from 50±12 to 274±54pg/kg of creative a few hours after coronary angioplasty (p<0.01). The increase excretion persisted for more than 24 hours. It was found that systolic aortic pressure was correlated with basal uninary excretion of ET-l within the range of nomal (r=0 87, p<0.01, n=15), but balloon size, dilating times and duration were not associated with ET-l level.Conclusion ET-l concentration of patients with coronary heart disease was higher than the control subjects. Vascular injury during coronary angioplasty increase urinary ET-l levels a few hours after the procedure. This increase was not detectable by sampling of femoral artery blood. Systolic aortic pressure was related to urinary ET-l. Larger clinical studies are required to further elucidate the biologic importance of endothelin in patients with coronary heart disease.