A new problem-based course in molecular biology, genetics, and cancer for first-year veterinary students was developed at the College of Veterinary Medicine at Cornell University (New York). The course was developed out of a desire to foster student-centered and lifelong learning and to integrate basic and clinical science knowledge despite a lack of established hierarchies or authoritative texts. The course was first offered in 1993 using problem-based methods and was organized around seven case scenarios intended to be investigated by 14 six-person groups each working with one faculty member. Though faculty were pleased with the course outcome, students expressed a need for greater clarity on course structure and difficulty locating resource material. Minor course design changes were made and the second iteration of the course was better received by students. Student performance did not change but students' perception about what they learned and how it related to veterinary medicine was more positive. The improved student attitudes are attributed to a better "fit" between the implicit and explicit structure of the course. The importance of monitoring the quality of students' learning is discussed as is the role of concept maps for structuring and assessing understanding. (Contains 14 references.) (JB)