The recent 100-year anniversary of the Flexner review and the release of the Australian Medical Education Study have stimulated vigorous debate about the role of bioscience knowledge in medical education. Two critical questions define debate in this area: does bioscience learning assist in educating medical students to become competent doctors, and, if so, what are the most effective teaching and learning methods to facilitate this outcome? There is tacit acceptance that specific bioscience knowledge is critical for the development of clinical expertise; however, there are few empirical data to support this notion. Two differing theories have been proposed to describe the role of bioscience learning in the development of clinical reasoning skills - the "two-worlds" model and the "encapsulation" model. A series of studies provides support for the encapsulation model. Some medical programs are now integrating bioscience teaching into the clinical years of the course. Evidence of the effectiveness of this on outcomes, such as improved clinical reasoning, is inconclusive.