• The aims of the study were to identify indicators of quality of nursing care from the perceptions of patients and nurses, and to determine the congruence between patients' and nurses' perceptions.
• The paper is presented in two parts. Part 1 includes the background and methods to the study and the findings from the comparison of patients' and␣ nurses' perceptions. Part 2 describes the perceptions of patients and nurses,␣ and the conclusions drawn from the study as a whole.
• Patients and nurses in hospital wards were interviewed using the critical incident technique.
• We grouped 4546 indicators of high and low quality nursing care generated from the interview transcripts into 316 subcategories, 68 categories and 31 themes.
• Congruence between patients' and nurses' perceptions of quality was high and significant, although there was some difference of emphasis.