This paper analyses a detailed data set on drugs in human clinical trials around the world between 1989 and 2002. The data provides information on the probabilities with which drugs successfully complete the different phases of the trials and the durations of successful completions. The paper shows that success rates and durations can vary substantially across observable characteristics of the drugs, including primary indication, originating company, route of administration and chemistry. It suggests that analysis of this type of data can help us to answer questions such as: Do AIDS drugs get to market faster? Do Biotech drugs have higher probabilities of getting to market? This paper provides some general statistics for analyzing these questions.