OBJECTIVES: Prior research documents that discontinuation rates among selective serotonin reuptake inhibitor (SSRI) users are high, but little is known about the likelihood of refilling at least one prescription. This study compares rates of first refills across SSRIs that remain on patent. METHODS: This retrospective cohort study used an administrative database from January 1, 1999 to June 30, 2002. Patients were followed up to 6 months after the first branded SSRIs. "Refill" was defined as refilling the first prescription for SSRIs of interest within 15 days or 1.5 times days supply. Logistic regression and sensitivity analyses examined the impact of age, gender, and co-payment as covariates. RESULTS: Based on descriptive analyses, sertraline, patients (N =5590; 54.70% refill; p = 0.0001) or citalopram patients (N = 4124; 54.49% refill; p = 0.0008) were more likely to have a refill than paroxetine patients (N = 5201; 50.99% refill). These results were consistent with the logistic regressions where covariates were significant at the p <0.10 but not the p <0.05 level. CONCLUSIONS: The likelihood of refilling an SSRI varies by the specific SSRI and may vary by age, gender, and copayment amount. Patients are more likely to refill the first prescriptions for sertraline or citalopram than for paroxetine.