Prior research has shown that exogenous shocks to the demand for medical products spur additional product development. These studies do not distinguish between breakthrough products and those that largely duplicate the performance of existing products. In this paper, we use a novel data set to explore the impact of the introduction of Medicare Part D on the development of new biotechnology products. We find that the law spurred development of products targeting illnesses that affect the elderly, but most of this effect is concentrated among products aimed at diseases that already have multiple existing treatments. Moreover, we find no increase in products targeting orphan disease or those receiving either fast track or priority review status from the FDA. This suggests that marginal changes in demand may have little effect on the development of products with large welfare benefits.