The World Health Organisation first identified, in 1975, the need for health professionals to be educated in the area of sexuality. Since then, studies exploring aspects of educational preparation of general nurses in relation to sexuality, found that there was an 'absence' of education in this area of practice. This paper reports findings on the educational discourses that shape mental health nurses' understandings of sexuality. Unstructured interviews were conducted with 27 consenting mental health nurses working in the Republic of Ireland. Data were analysed using the principles of Grounded Theory. Findings suggest that participants were exposed to a subtle network of legitimised sexual discourses during primary, secondary, and professional socialisation. These discourses provided participants with a view of sexuality that emphasised taboo, privatisation, pathology, and control. Social, political, or rights-based discourses that could have provided participants with the knowledge and clinical competence necessary to include sexuality in an open and confident manner within the horizons of nursing practice were absent. These findings challenge educators involved in curriculum development to rethink the fundamental philosophy that is shaping mental health nursing curricula. They also challenge educators to rethink their ideas around the meaning of 'absence' in relation to education.