Problem-based learning (PBL) methods have revolutionized the field of medical education, since its introduction almost 40 years ago. However, there are many un-answered questions on the benefits and effectiveness of PBL. The supporters and critics of PBL continue to dispute the merits of cognitive foundation of PBL based approach. This paper performs a literature review of the different systemic reviews and meta-analysis which have addressed the effectiveness of PBL. Evidence presented in these reviews show that PBL does not impact knowledge acquisition, but impacts application of knowledge. There is no unequivocal evidence in favour of PBL that it enhance learning. More work is needed to identify appropriate outcome measures in-order to analyze the effectiveness of PBL.