BACKGROUND AND AIMS: This study was designed to determine whether the haptoglobin levels are comparable to the antioxidant status levels. 40 athletes and 30 volunteers were enrolled in the study. MATERIAL AND METHODS: Blood samples for serum malondialdehyde (MDA), total antioxidant status (TAS), haptoglobin, glucose, total cholesterol (TC), triglyceride (TG), very low density lipoprotein cholesterol (VLDL-C), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) and lipoprotein (a) (Lip a) determinations were obtained before and after cyclists completed 300 km bicycle ride. RESULTS: Comparison of the results between the cyclists and control group yielded a significant difference in serum levels of TG, VLDL-C and LDL-C (P<0.05). The cycling induced a significant increase in HDL-C, VLDL-C, TG, MDA and TAS levels (P<0.001). Serum LDL-C and Lip a levels were greater before than after cycling (P<0.05). There was no significant difference among precycling and postcycling haptoglobin levels, whereas the haptoglobin level in control group was significantly higher than in the cyclists (P<0.001). CONCLUSION: The change in serum antioxidant and lipid levels due to physical activity must be explained as a consequence of the duration of exercise. Further studies are needed to demonstrate haptoglobin’s possible role in decreasing oxidative stress during exercise.