Regulatory reform is often seen as a road paved by good intentions, but leading to ‘policy hell’. The example of the railways seems to represent a prime example of regulatory failure, not only in Britain but also in Germany. This article analyses the notion of ‘regulatory failure’ in the railway domain by taking an analytical and a comparative perspective. First, it introduces a variety of explanations as to why regulation can go wrong. Second, it considers the design and the consequent evolution of the regulatory regimes for the railways in Britain and Germany since the early 1990s. Both countries offer similar life-cycles of regulatory reform, however differing in design, perceived failures and advocated solutions. Finally, it discusses how the literature on regulatory failure contributes to the understanding of British and German railway regulation and argues that any regulatory regime is not only characterised by a conflict of interests, but also by conflicts of standards of appropriateness that lead to inherent tension and potential causes for failure.