Post-menopausal hormone replacement therapies (HRT) represent a significant long-term pharmacological treatment that is associated with multiple beneficial clinical outcomes. However, HRT is associated with a significant reduction in patient compliance over time. OBJECTIVE: To determine the impact of periodically mailed patient educational materials on HRT compliance. METHOD: Using centralized pharmacy records from a managed-care organization, both retrospective baseline (12 months preceding mailings) and prospective (12 months following mailings) compliance indices were analyzed for three cohorts of patients: Cohort A = patients who were receiving material prior to program initiation; Cohort B = patients who were offered material but declined (Cohort B); Cohort C = patients who had not previously received material but elected to do so during the study period. Compliance indices included assessment of MED-INT (number of days of medication), MED-TOT (total medication) and MED-OUT (days without medication). Patients were identified as "compliant" if they had a MED-TOT >75% or a MED-OUT <25%. RESULTS: 584 patients (Cohort A=149, Cohort B=245 and Cohort C=190) were included in analyses. During the retrospective baseline period, all three cohorts had statistically similar compliance indices. Analyses of data collected during the prospective period indicated that, compared to Cohort B, significant (p<0.01) between-group improvements in each of the compliance indices were observed. Furthermore, the greatest overall improvements from baseline were observed in Cohort C and Cohort C demonstrated a significant (p <0.01) increase in number of "compliant" patients compared to Cohort B. CONCLUSION: These results suggest that educational material significantly improves patient compliance and the effect can be directly observed by assessing centralized pharmacy records.