This study investigated the effect of conjugated linoleic acid (CLA) on the aerobic capacity and anthropometric measurements of humans. Although this effect has been shown in animal studies, human studies have reported controversial results. In this double-blind, placebo-controlled, randomized clinical trial, 80 non-trained healthy young men received a 50:50 mixture of cis-9,trans-11 and trans-10 cis-12 CLA (CLA 4 × 0.8 g day(-1)) ora placebo (PLA; soybean oil) in an 8-week intervention. Maximal oxygen consumption (VO2 max), time to exhaustion, weight, body mass index (BMI) and waist circumference (WC) were measured. CLA had no effect on VO2 max (p = 0.5) also no change was seen in time to exhaustion (p = 0.51), weight (p = 0.7), BMI (p = 0.7) and WC (p = 0.8) vs PLA. Our results suggest that CLA has no significant effect on VO2 max, time to exhaustion and anthropometric measurements in untrained healthy young male students.