OBJECTIVES: Evaluate a patient Formulary Notification Program (FNP) designed to encourage use of lower cost, clinically equivalent generic alternatives among non-formulary atorvastatin users. METHODS: This was a cross-sectional, case-control study conducted in a commercially insured population, targeting current atorvastatin users (date of last fill + days supply within 30 days of targeting). The case group received one of two letter-based Patient Communications (PCs) depending on channel of most current prescription fill (target prescription). The PCs informed patients of lower cost, clinically equivalent generic alternatives. Patients in retail pharmacies (n=27449) received information on copayment savings from generic use in retail. Patients in Home Delivery (HD) (n=25274) received information on savings from filling generic alternatives in HD. The PCs were mailed in July 2006 soon after availability of generic simvastatin. The control group consisted of current atorvastatin users (at time of case group targeting) who were not enrolled in a client that implemented the FNP. Control group members were matched to case group based on distribution channel [retail (n=3186)/HD (n=1012)] of target prescription. Prescription claims were examined through October 2006 for the outcome of switching to generic statin. Bivariate and logistic regression analyses were used to assess research objective. RESULTS: In retail, 11.9% of cases switched to generic statin compared to 4.8% in control group (p<0.001). In HD, 20.6% of cases switched to generic statin compared to 8.1% in control group (p<0.001). Controlling for demographic and plan design, patients who received PCs in retail had 64% greater odds (95%CI:1.48-1.81) of filling generics relative to controls. Patients receiving PCs in HD had 81% greater odds (95%CI:1.60-2.05) of filling generics in HD compared to respective controls. CONCLUSION: Informing patients of copayment savings from generic alternatives soon after patent expiration of a popular branded statin, is an effective strategy to encourage greater generic statin use.