Caring is inextricably bound to the belief system and practice of nursing. Yet there is a lack of research on what caring is for the practising nurse. It was the purpose of this qualitative study to investigate the phenomenon of caring with 17 hospital staff nurses who, in taped sessions, described their subjective experiences of caring. Phenomenology, an inductive descriptive research method, was used with the data analysed according to Colaizzi's procedure. Thirty theme clusters, emerging from specific themes, fell into seven categories under two broad classifications; 'what is caring' and 'what affects caring'. The essential structure of caring is described and implications for nursing education, practice and research discussed.