Most mental health nurses engage at some point with clients who harm themselves and these nurses often experience strong negative emotional reactions. Prolonged engagement with relapsing clients can lead to antipathy, and ‘malignant alienation’. The study reported here has the aim of developing a brief, robust instrument for assessing nurse attitudes in this area. The Self-Harm Antipathy Scale, developed here on a sample of 153 healthcare professionals, has 30 attitudinal items with six factors. It has acceptable face validity, good internal consistency and some evidence of good test–retest reliability. It discriminates effectively between criterion groups. Overall this is evidence for the complexity of nurses' responses to this client group but such complex attitudes can still be assessed using a relatively brief structured instrument.