Since the early 1990s, there has been an organizational race to implement business process re-engineering (BPR). Many BPR methodologies and variations have been proposed by both academicians and practitioners, but a close look at the concept of BPR emerged from observing the practices of highly successful organizations in the 1980s and early 1990s. Thus, to understand truly BPR one has to learn from the world of organizational experience. It is vital to look at what others have done, their feedback, mistakes, results and overall approach to re-engineering. This paper provides a critical review of 79 case studies from the re-engineering literature. It introduces a review of a wide spectrum of case studies, studying the various approaches, methodologies and tools applied to assess the applicability of BPR concepts universally, the applicability within different organizational types and sectors, the actual results achieved, and the critical success factors and major challenges from the viewpoint of practitioners. [ABSTRACT FROM AUTHOR]