PURPOSE: To examine the effects of an employer-based monetary incentive program on membership termination and usage at a fitness center. DESIGN: Retrospective nested case-control study examining the relationship between participation in an incentive program, visits to the fitness center, and membership termination at 1 year. SETTING: University-based fitness center. PARTICIPANTS: Members (N = 1122) of a university-based fitness center. INTERVENTION: Members were offered either a US$25 incentive for each month they visited the fitness center at least 10 times or no incentive. MEASURES: Data were extracted from the membership database and included membership termination at 1 year (yes, no), length of membership (days), participation in the incentive program (yes, no), and visits to the fitness center per month. ANALYSIS: Cox proportional hazards model. RESULTS: Members in the incentive program visited the fitness center on average more times per month (5.3 vs 4.3; P < .0001) but were significantly more likely to terminate memberships at 1 year compared to members who did not receive the incentive (38% vs 31%; P = .013). After controlling for relevant covariates, members who received the incentive had a 24% greater hazard of terminating their memberships compared to members who did not receive the incentive (hazard ratio [HR] = 1.24; P = .041). After controlling for the number of visits per month, the incentive program was no longer significantly related to membership termination (HR = 1.21; P = .07). CONCLUSION: Being in a monetary incentive program to attend a fitness center may be initially associated with a greater fitness center utilization but may not be associated with a reduced risk of membership termination.