OBJECTIVE: To investigate mean creatine kinase (CK) levels in National Collegiate Athletic Association (NCAA) Division I football athletes and the relationship between mean CK levels and demographic variables. DESIGN: Observational cohort. SETTING: NCAA Division I football program. PARTICIPANTS: NCAA Division I football athletes. INTERVENTIONS: Blood and urine samples were obtained from 32 athletes on the first (time 1), third (time 2), and seventh (time 3) days of football camp. MAIN OUTCOME MEASURES: Mean CK levels. The hypotheses were formulated before the data were collected. RESULTS: All urine samples tested negative for blood. Mean CK levels were 284.7 U/L at time 1, 1299.8 U/L at time 2, and 1562.4 U/L at time 3. The increases in means were statistically significant (P < 0.005 for all pairwise comparisons). Most demographic variables were not related to mean CK levels. The number of days in the precamp conditioning program was negatively associated with mean CK levels (P = 0.0284). CONCLUSIONS: Mean CK levels in NCAA Division I football athletes during camp were higher than the serological criteria for rhabdomyolysis commonly used in clinical practice. More data are needed to assess if the number of days of participation in precamp conditioning is related to lower CK levels in NCAA Division I football athletes during camp.