Electronic prescription (e-prescribing) gives information about formularies right at the point of service. The aim of this research was to evaluate the impact of e-prescribing on formulary adherence and the use of generic medications. METHODS: This was a retrospective examination of pharmacy claims data from a significant national managed care company. We randomly chose a group of 95 physicians that mostly used e-prescribing (the e-prescriber group). A matched sample of 95 conventional prescribers was chosen (traditional prescriber group), aligned with the e-prescriber group based on zip code and medical specialization. To see how e-prescribing affects formulary compliance and generic use, we looked at 110,975 paid pharmacy claims from August 1, 2001, to July 31, 2002. We looked at all paid pharmacy claims for each group. For the e-prescriber group, this meant looking at all claims, not just those that were made using an e-prescribing device. A written qualitative survey was sent to doctors and office managers to find out how often they use e-prescribing, where they get their formulary information, and how e-prescribing affects office resources.