This paper is divided into five sections; the first describes the data, which are collected from retail pharmacies and provide comprehensive information on the prescription drug sales transaction. Prescription characteristics, e.g. amount of drug dispensed, daily dosage regimen, patient cost, etc., and information about the prescribing physician are readily available. The data sample, itself, is a very large one (37% of the population), and is geographically well-distributed. It is capable of providing statistically accurate estimates of product performance, in small areas, on a weekly or monthly basis. The second section places these data in the context of currently available alternatives. These alternatives are inventory measures, and, as such, are confounded by pipeline effects. Although inventory order patterns are related to the brand choices made by physicians, the nature of that relationship, in both time and space, is complex and obscure. For prescriber data, this critical relationship is absolutely clear. The third section discusses the application of these data for sales management. Two applications are considered; managing sales representatives through objective setting and performance evaluation, and managing territories to improve targeting and sales performance. The fourth section describes three applications of these data for market research; promotion research/sales response modelling, brand switching analyses, and examination of prescribing trends in initial therapy starts. Because these data are a direct measure of individual brand selection decisions, they offer an ideal dependent variable for market research investigations. The fifth and final section simply summarizes the most salient points of the preceding sections, and puts forth the conclusion that, for the first time, with the data available from Walsh America - Pharmaceutical Data Services, both sales and marketing can employ a single resource to improve performance.