The notion of harm is frequently used in the discussion of the nature of mental disorder. Harm also plays important roles in the prominent diagnostic manuals such as DSM and ICD. Recently, however, Cristina Amoretti and Elisabetta Lalumera have questioned the idea that harm should be a necessary constituent of mental disorders. They argue that the notion of harm is underspecified and potentially leads to false negatives in diagnosing mental disorders. Given that harm plays significant roles in medical diagnosis and (...) treatment indicates that we should be reluctant to remove it as a criterion for deciding whether some condition is a mental disorder. Instead, we argue that harm should be understood in the prudential sense and harm in this sense provides a way of responding to worries raised by Amoretti and Lalumera, while staying true to the conception of harm that is relevant for psychiatric practice. (shrink)