The prevalence of Internet applications nowadays has led many medical schools and centers to incorporate computerized Problem-Based Learning (PBL) methods into their training curricula. However, many of these PBL systems do not truly reflect the situations which practitioners may actually encounter in a real medical environment, and hence their effectiveness as learning tools is somewhat limited. Therefore, the present study analyzes the organization of a computerized PBL teaching case, and considers how a clinical teaching case can best be presented to the user. Specifically, this study attempts to develop a web-based PBL system which emulates the real clinical situation, in which a practitioner will ascertain the true nature of a patient's condition over a period of time, by introducing the concept of a "time sequence" within each teaching case. The proposed system has been installed in the medical center of National Cheng Kung University in Taiwan for testing purposes. The feedback received confirms the effectiveness of the training system in allowing users to apply their basic medical knowledge to real clinical cases, and in identifying their areas of misconception in the course of a medical diagnosis. (Contains 1 table and 5 figures.)