This paper is concerned with how roles within one group general practice are perceived to have been affected by the introduction of the nurse practitioner into the primary health care team (PHCT) for a 2-year pilot period. The data presented are from data elicited during a single round of interviews with patients ( n = 30) and two rounds of interviews with all medical and nursing staff within the primary health care team on two occasions (40 interviews). The patient interviews were undertaken in the first year of the study, and interviews with staff were undertaken within 6 months of the commencement of the study and during the final 6 months. The overall aim was to evaluate the feasibility of the role and its possible future application to other primary health care settings. This paper will discuss the findings of that aspect of the study relating to the effects on role boundaries between doctors and nurses, and between nurse practitioner and nurses, midwives and health visitors in the practice as perceived by the patients, nurses and doctors involved. The nurse practitioner in this particular practice was a very experienced practice nurse with a wide range of knowledge and skills which she brought to the nurse practitioner role. This, together with well-organized teaching and supervision in the practice setting and a structured programme of formal education, resulted in a highly effective practitioner who was generally seen to have blurred the boundary lines between medical and nursing roles.