For many within the nursing profession, the work role involves a great deal of emotional work or ‘emotional labour’. Such emotional work can be performed through ‘surface acting’ in which the individual simply feigns an appropriate emotion, or through ‘deep acting’ in which they actually try to feel the required emotion. The current study aims to aid understanding of the complex relationship between components of emotional labour and stress within the mental health nursing sector. Thirty-five mental health nurses completed questionnaires relating to a total of 122 nurse–patient interactions. Data were collected in relation to: (1) the duration and intensity of the interaction; (2) the variety of emotions expressed; (3) the degree of surface or deep acting the nurse performed; and (4) the perceived level of stress the interaction involved. Nurses also completed Daily Stress Indicators. Results suggest that: (1) emotional labour is positively correlated with both ‘interaction stress’ and daily stress levels; (2) the deeper the intensity of interactions and the more variety of emotions experienced, the more emotional labour was reported; and (3) surface acting was a more important predictor of emotional labour than deep acting. Implications for mental health nurses are outlined.