The pharmaceutical industry has long been one of the most innovative industries and, unlike industries such as computers and aircraft, has remained relatively unconcentrated. In recent years, however, there have been contrasting industry developments that could have far-reaching, long-run effects on the industry's structure. This paper examines the impact of the entry of new biotechnology firms, the increasing real cost of innovation, and the recent important mergers among leading firms. Also, a regression analysis reveals disproportionately high innovative contributions from both new biotechnology firms and the very largest multinational pharmaceutical firms.