The drug development environment has undergone considerable change as it adjusts to changing technology, changing attitudes about the need to make safe and effective drugs available to the public as quickly as possible and, as it adjusts to the internationalization of the pharmaceutical industry and international harmonization of drug regulation. At the same time, there has been a growing interest in the technical standards for Systematic Reviews of clinical studies emerging in a regulatory setting. Also, there has been a continuing interest in ways of taking full advantage of the information from clinical studies, both individually and collectively, and an ongoing interest in the role of Systematic Reviews as a source of evidence in a drug regulatory process.

This paper looks at Systematic Reviews from the perspective of drug development, review and approval process, especially as seen from the peresective of an FDA statistician in the United States. Special attention is given to distinguishing between the Systematic Reviews encountered in the evaluation of new drug efficacy and the Systematic Review encountered in the evaluation of new drug safety.

In this context, the issue of what constitutes evidence in the regulatory decision process is developed. The paper answers the question "Can Systematic Reviews provide The Evidence for Making Regulatory Decisions? In answering this questions some of the uses and limitations of Systematic Reviews are discussed and clarified.