Introduction: Professional nursing is increasingly often understood as accompanying and assisting people during health, disease and limited fitness. It is also shaping their self-care capabilities. The complexity of these tasks puts great responsibility on nurses, since they are those health care professionals who are in direct contact with patients’ families and communities. Nurses’ functions are exceptional because they involve the management and organization of holistic care in work with patients and their families (nursing and educational activities, cooperation with other members of a therapeutic team).The purpose of this study was to analyze their level of knowledge concerning their tasks and professional competences in family nurse practitioners employed in primary health care centers.Materials and methods: The research were carried out from February 2014 to the end of October 2015 in entities providing nursing services in primary health care in north-western Poland. For the analysis 643 questionnaire surveys were accepted.Results: Family nurse practitioners in north-western Poland show a satisfactory level of knowledge in the field of professional competence. Nurses have especially high levels of knowledge concerning patients’ access to nursing services, information provided by primary care physicians as part of cooperation in the care of a patient, the nursing process method, and care of elderly and chronically ill individuals. The nurses had gaps in their knowledge of selected nursing services, such as bladder irrigation, transport, and rectal procedures. Alarmingly low levels of knowledge were observed with regard to professional competence in the care of patients with mental diseases.