PURPOSE: To examine the relationship between serum 25 hydroxyvitamin D concentration ([Vit D]), serum ferritin concentration ([Fe]) and athlete burnout (AB) in Division I (D1) collegiate athletes. METHODS: Seventy-two (males = 24) DI college athletes (cross-country, swimming, basketball, women’s soccer) completed blood draws and psychosocial measurements both pre- and post-competitive season. Serum was analyzed for 25 hydroxyvitamin D and ferritin at a certified hospital laboratory. The athlete burnout questionnaire (ABQ) was completed post-competitive season (Raedeke & Smith, 2001). Subscales of ABQ include devaluation of sport, emotional and physical exhaustion, and reduced sense of accomplishment. RESULTS: Linear regression analyses on the entire cohort (male and female athletes combined) revealed no statistically significant relationships between pre-to post-competitive season change (Δ) for either Δ[Vit D] (p = .78) or Δ[Fe] (p = .69) with regards to any subscale variable within the ABQ. When separated by gender, Δ[Vit D] (p = .57) and Δ[Fe] (p = .57) did not significantly predict AB in females. However, a significant decrease in pre to post competition Δ[Vit D] (Mean±SD = -8.45±4.33) did significantly predict and explain 20.6% of the variance of male athlete perceptions of devaluation of sport (p < .05). Another linear regression showed that pre-season [Fe] (Mean±SD = 68.53±31.49) predicted and explained 16% of the variance of male athlete perceptions of physical and emotional exhaustion from sport (p ≤ .05). Additionally, medium to large correlations were noted in male athletes between [Fe], [Vit D], and AB including pre-season [Fe] and AB (r = .41:p<0.05), post-season [Fe] and AB (r = .36;NS), and Δ[Vit D] and AB (r = .41;p<0.05). CONCLUSION: These preliminary findings support a proposed interplay between mood and chemistry, with respect to Δ[Vit D], Δ[Fe], and AB, particularly in male collegiate athletes who live and train in latitudes above 37 degrees north (Vitamin D winter). Although significant negative relationships were found in male athletes only (the lower [Vit D] and [Fe], the greater chance of AB) we will continue exploration in both genders with randomized (supplement) trials, greater number of subjects, and extended testing time through the winter.