The purpose of this study was to determine the effect of six-week high intensity interval training (HIIT) on fibrinolytic factors (t-PA, PAI-1 & t-PA/PAI-1) in sedentary young men. Eighteen inactive young men voluntarily took part in this study and were randomly divided into two groups including the experiment group (n: 9, age: 24.33 ± 1.41, height: 176.22 ± 4.91 and weight: 72.27 ± 6.59) and control group (n: 9, age: 23.27 ± 2.01, height: 180.22 ± 6.88 and weight: 76.27 ± 7.33). The experiment group performed three weekly HIIT sessions over 6 weeks. Each session consisted of either four to six repeats of maximal sprint running within a 20m area with 20–30s recovery. The control group was instructed to continue their normal behavior. Fasting blood samples were collected 24 hours before and 48 hours after the exercise protocol. The obtained data were analyzed using independent t-test. The results showed that the resting levels of PAI-1 were significantly reduced in the experiment group compared to the control group (P=0.012). However, there was no significant difference between the t-PA and complex t-PA/PAI-1 levels after exercise intervention compared to the control group (P=0.257 & P=0.127). Also, the present study showed a significant increase in VO₂max and plasma volume. In contrast, it revealed a significant body fat decrease in the participants of the experimental group compared to the control group. Overall, it appears that a six-week HIIT not only effectively reduces body fat but also increases aerobic fitness, and, more importantly, leads to improvement of the fibrinolysis process in sedentary young men.