Considering that PAI-1 is an important factor modulating the systemic fibrinolytic activity, the abnormal insulin metabolism frequently seen in end-stage renal disease (ESRD) may cause decreased fibrinolytic activity in concert with PAI-1. To study this possibility, we measured insulin levels and compared it with the fibrinolytic profiles in ESRD patients. Fasting blood sugar, insulin, and C peptide levels were higher in ESRD patients than in the control group. In the ESRD patients, the insulin levels showed a positive correlation with C peptide (r=0.612, p=0.0001), fasting blood sugar (r=0.334, p=0.044), and PAI-1 antigen (r=0.474, p=0.0001) and a reverse correlation with euglobulin fibrinolytic activity (r=0.5, p=0.005), but no correlation with t-PA antigen. The euglobulin fibrinolytic activity showed a reverse correlation with PAI-1 antigen (r=0.289, p=0.0144), but no correlation with t-PA antigen. Our results suggest that abnormal insulin metabolism and/or insulin resistance, which occur frequently in ESRD, may play an important role in the decrease in systemic fibrinolytic activity by the regulation of the PAI-1 concentration.