Oxidative stress is a physiological condition in which reactive oxygen species created through cellular respiration can potentially damage DNA and tissue. Oxidative stress may partially mediate trade-offs between reproductive effort and survival efforts. On the one hand, traits associated with reproductive effort, particularly costly male-male competition, are expected to raise oxidative stress. On the other hand, behavioral strategies may be a critical mediating mechanism, such that those who can better resist the physiological costs of oxidative damage exhibit increased mating effort. In a sample of 248 college students (173 men), we examined the associations between traits linked to mating effort—including personality features, athleticism, and history of illness—with levels of 8-OHdG, a biomarker of oxidative stress. 8-OHdG was measured twice, one week apart, once during active hours and once at awakening. In men, surgency, social dominance, and athleticism were all negatively associated with 8-OHdG levels in awakening, but not lab samples collected during active hours. In women, these same traits were positively associated with 8-OHdG levels, particularly in morning samples. Differences in associations based on sex and time of collection introduce additional complexities to understanding links between oxidative stress and mating effort.