The general definition of mental disorder stated in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders seems to identify a mental disorder with a harmful dysfunction. However, the presence of distress or disability, which may be bracketed as the presence of harm, is taken to be merely usual, and thus not a necessary requirement: a mental disorder can be diagnosed as such even if there is no harm at all. In this paper, we focus on the (...) harm requirement. First, we clarify what it means to say that the harm requirement is not necessary for defining the general concept of mental disorder. In this respect, we briefly examine the two components of harm, distress and disability, and then trace a distinction between mental disorder tokens and mental disorder types. Second, we argue that the decision not to regard the harm requirement as a necessary criterion for mental disorder is tenable for a number of practical and theoretical reasons, some pertaining to conceptual issues surrounding the two components of harm and others pertaining to the problem of false negatives and the status of psychiatry vis-à-vis somatic medicine. However, we believe that the harm requirement can be maintained among the specific diagnostic criteria of certain individual mental disorders. More precisely, we argue that insofar as the harm requirement is needed among the specific diagnostic criteria of certain individual mental disorders, it should be unpacked and clarified. (shrink)