Abstarct: The purpose of this study was to survey effect of caffeine supplementation intake at different times lower limb muscle endurance performance in elite distance runners. For this purpose 13 subjects with mean age (19.07±2.72 years) and BMI (21.12±2.04 kg/m2) voluntary participated in this study. Research was quasi-experimental and was done in singel-blind design with subjects participating in four times within three days of each other in one of the four: 1-placebo, 2- Caffeine 30 minutes before the test, 3- 60 minutes before the test and 4- 150 minutes prior to the test (6 mg/kg) Respectively. In each session, subjects, Bruce test to exhaustion for the aerobic, anaerobic Wingate test the ability to function (peak power, average power and fatigue index) and repeat the test until exhaustion with 70 percent of 1RM Squat reached for muscular endurance run out. Data was analyzed with kolmogrov-smirnov and repeated measure (p≤0/05). The results showed that supplementation of caffeine 30 minutes before the test compared to placebo resulted in a significant increase in aerobic performance (P=0/001), 150 minutes before the test compared to placebo resulted in a significant increase in peak anaerobic power (P=0/010), 60 minutes before the test compared to placebo resulted in a significant increase in the mean anaerobic power (P=0/001), 30 minutes prior to the test significant increases muscular endurance compared with placebo (P=0/025) and 30 minutes before the test compared to placebo, meeting was the significant increase in the volume of muscular endurance test (P=0/036). The results showed that caffeine supplementation (6mg/kg) at 30 minutes before the activity increases the maximum oxygen consumption (vo2max), 60 minutes before the activity increases mean anaerobic power, anaerobic power peak of 150 minutes before the activity increases and 30 minutes before the activity is to increase muscular endurance and muscular endurance test volume.