This study is the fifth in a series that documents changes in the status of drug development in the United States based on a survey of the pharmaceutical industry. For example, the study shows that, although there has been a recent increase in the number of new chemical entities being tested by US firms, an increasing proportion are acquired from outside the firm. Moreover, a growing number of acquired new chemical entities are coming from sources outside the United States, particularly Japan. These and other trends suggest an overall decline in research activity in the United States. At the same time, foreign firms are becoming more active, foretelling greater competition in the United States for both market share and research resources. The analyses also show a continued increase in synthesis-to-approval time, surpassing 13 years in the early 1980s, and rising success rates, reaching about 12% by the late 1970s.