Background The lack of a standardised nursing taxonomy to clarify nurses’ assessments and other elements of the nursing process can potentially lead to a lack of care continuity and patient safety. The taxonomy published by NANDA International (NANDA-I) has been shown to improve the quality of mental health nurses’ documentation and clinical care.

Aim To describe nurses’ experience of working in mental health inpatient care with a structured nursing taxonomy of diagnoses based on the NANDA-I taxonomy.

Method Semi-structured interviews were conducted with five nurses working on three inpatient wards in a mental health unit in Sweden. The data were analysed using qualitative manifest content analysis.

Findings The nurses’ experiences of using the NANDA-I taxonomy were described through three themes: ‘benefits of having a common language’, ‘usefulness of the NANDA-I taxonomy in the mental health context’, and ‘importance of how healthcare organisations apply the NANDA-I taxonomy’.

Conclusion The common language provided by the NANDA-I taxonomy contributed to making nursing care more structured and person-centred. However, for the NANDA-I taxonomy to be effective, local nursing guidelines need to be synchronised with it.