This article examines the impact of direct-to-physician, direct-to-consumer, and other marketing activities by pharmaceutical companies on a mature drug category which is in the later stage of its life cycle and in which generics have accrued a significant market share. The main objective of this article is to quantitatively estimate the impact of pharmaceutical promotions on physician prescribing behavior for three different statin brands, after controlling for factors such as patient, physician and physician practice characteristics, generic pressure, et cetera. Using unique panel data of physicians, combined with patient pharmacy prescription records, the authors developed a physician level generalized linear regression model. The generalized estimating equations method was used to account for within physician serial correlations and estimate physician population averaged effects. The findings reveal that even though on average the marketing efforts affect the brand share positively, the magnitude of the effects is very brand specific. Generally, each statin brand has its own trend and because of this, the best choice of predictors for one brand could be suboptimal for another.