Aims. This paper reports findings from a large-scale quasi-experimental study that used a measure of caring as a means of evaluating person-centred nursing and aims to illustrate the synergy between the concepts of caring and person-centredness.Background. Evidence would suggest that effective person-centred nursing requires the formation of therapeutic relationships between professionals, patients and others significant to them in their lives and that these relationships are built on mutual trust, understanding and a sharing of collective knowledge. This correlates with the conceptualisation of caring that is underpinned by humanistic nursing theories.Design. A pretest post-test design was used in this study to evaluate the effect of person-centred nursing on a range of outcomes, one of which was nurses' and patients' perception of caring.Methods. The Person-Centred Nursing Index was the main data collection tool. The Caring Dimension Inventory and Nursing Dimensions Inventory, were component parts of the Person-Centred Nursing Index and were used to measure nurses' and patients' perceptions of caring. The Person-Centred Nursing Index was administered at five points in time over a two-year intervention period.Results. Nurses had a clear idea of what constituted caring in nursing, identifying statements that were reflective of person-centredness, which was consistent over time. This was in contrast to patients, whose perceptions were more variable, highlighting incongruencies that have important implications for developing person-centred practice.Conclusion. The findings confirm the Caring Dimension Inventory/Nursing Dimensions Inventory as an instrument that can be used as an indicator of person-centred practice. Furthermore, the findings highlight the potential of such instruments to generate data on aspects of nursing practice that are traditionally hard to measure.Relevance to clinical practice. The findings would suggest that nurses need to be aware of patients' perceptions of caring and use this to influence changes in practice, where the prime goal is to promote person-centredness.