This study compared the acute immune response, inflammation, and lipid peroxidation to a 75km cycling time trial in male athletes testing positive or negative for latent cytomegalovirus (CMV) infection. Trained cyclists (N=20) were tested for CMV serostatus, and cycled 75km on a mountainous course using indoor trainers with continuous workload monitoring. Pre-, post-, and 1h post-exercise blood samples were analyzed for total blood leukocyte counts, blood granulocyte (GR) and monocyte (MO) phagocytosis (PHAG) and oxidative burst activity (OBA), four plasma cytokines, and plasma F2-isoprostanes. Forty percent of the subjects tested positive for CMV. No differences in subject characteristics were found between CMVpos and CMVneg groups. Mean power (57.3±1.6, 59.4±1.8% maximal Watts, p=0.803), heart rate (87.0±1.0, 86.5±1.3% maximal heart rate, p=0.376), and total time (2.56±0.08, 2.60±0.08h, p=0.744) to complete the 75km cycling time trial did not differ between CMVpos and CMVneg groups. Whereas exercise induced significant changes in total blood leukocyte counts, GR and MO-PHAG, four plasma cytokines, and plasma F2-isoprostanes (p<0.05, ω(2)>0.03), these exercise-induced changes did not differ between CMVpos and CMVneg groups (p>0.05, ω(2)<0.01). CMV serostatus does not appear to influence these innate immune responses or markers of inflammation and lipid peroxidation in response to a single bout of heavy exertion.