Aims: To explore mental health nurses' knowledge, attitudes and clinical judgement concerning medicines management in an inpatient setting with a view to enhancing training. Background: Medicines management is a key role of mental health nurses, but little research has been conducted into their training needs. Design: An exploratory mixed-methods design was used involving individual interviews with participants to investigate their responses to hypothetical medicine administration scenarios. Methods: Interviews were held with a convenience sample of 50 Registered Nurses working in a specialist mental health hospital between November 2012-February 2013. Participants were presented with clinical vignettes describing eight scenarios they might encounter as part of their medicines management role and asked about how they would respond. Responses were assessed by two independent raters against ten quality standards underpinning the vignettes. Results: The median number of responses that were judged to demonstrate adequate awareness of associated quality standards was 4 (range 1-7), indicating that many participants did not appear to be aware of, or compliant with, current UK medicines management guidance and local policy. Many would not report a 'near miss' or medicines administration error. There was a lack of awareness of guidance on verbal prescribing, consent to treatment rules and the administration of off-label/unlicensed drugs. Past year attendance on a medicines management course, time since registration and self-reported knowledge of national standards for medicines administration did not discriminate between total score on the 10 quality standards. Conclusion: The medicines management training needs of participants appeared not to be fully met by the existing learning sources. The use of vignettes to assess nurses' training needs requires evaluation in other settings.