Background: The inclusion of a new mental disorder in the nomenclature is not a trivial matter. Many have highlighted the risks of an ever-increasing number of mental disorders and of overpathologizing human behaviour. Given the proposed inclusion of a new hoarding disorder (HD) in DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, fifth edition), it is pertinent to discuss the potential benefits and pitfalls of such a development. Method: In this article, we examine whether HD fits with the current DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, fourth edition) and proposed DSM-5 definitions of "mental disorder". We next discuss the potential benefits and risks of the creation of this diagnosis. Finally, we address some additional considerations that may arise when proposing a new disorder for the nomenclature and identify some of the gaps in the knowledge base. Conclusion: HD fits the current DSM-IV and proposed DSM-5 definitions for a mental disorder. On balance, the potential benefits of creating the new diagnosis (e.g. identification of the majority of cases who clearly suffer and need help but are currently missed out by the existing diagnostic categories) outweigh the potential harms (e.g. pathologizing normal behaviour). Whether the criteria will need modification for their use in children/adolescents is unclear and more research is needed to address this question.