Problem-based learning(PBL) is defined as a process of acquiring understanding, knowledge, skills and attitudes in the context of an unfamiliar situation, and applying such learning to that situation. PBL is a way of enabling students thinking more efficiently than they can do in the traditional methods of largely rote learning. Because mordern medical knowledge is growing at an enormous rate, PBL is though as a mean to cope with the rapidly increasing, rapidly changing information base of medicine. The definition, goals, practice, strength, and problems of PBL in medical education are discussed. The curriculum and educational philosophy of McMaster Medical School, where PBL in small group tutorials predominates the programme, are also introduced. Hinderences from implementing PBL in our medical education are discussed.