This study aimed to verify the risk factors associated with gym regulars’ dropout over 12 months. This is an observational, retrospective, cohort study. The sample consisted of two gyms (Gym 1: n=2027, age=39.1 ±13.1 years; Gym 2: n=1775, age=36.8 ±11.6 years). Each participant was followed up for 12 months, or until dropout, by controlling the biometric entry system using a turnstile. The adherence rate was of 11% at Gym 1 and 19% at Gym 2. At both gyms, training frequency ≤3x/month and 4-6x/month was associated with dropout. At gym 1, being a female, aged ≥43 years, and enrollment between October and December were dropout predictors. At Gym 2, dropout was associated with contract length ≤31 days and 32-186 days and enrollment between April and December.