Assertiveness is considered healthy behaviour for all people that, when present, mitigates against personal powerlessness and results in personal empowerment Nursing has determined that assertive behaviour among its practitioners is an invaluable component for successful professional practice The purpose of this descriptive study was to determine assertiveness levels of a population of professional nurses and to determine if assertiveness levels are related to selected demographic factors including age, gender, years of nursing experience, basic nursing education, clinical nursing speciality, type of employer, highest educational level and prior assertiveness training The sample was composed of 500 registered nurses (64% response rate), chosen randomly from the list of active licensees registered with the Minnesota (USA) State Board of Nursing, who completed and returned an assertiveness questionnaire The questionnaire consisted of the Rathus Assertiveness Schedule (RAS) and a personal/ professional data form Data analysis included descriptive as well as inferential statistics The results revealed that this group of nurses was more assertive than any other group of nurses or non-nurses reported in the literature using the RAS The oldest group of nurses (60–76 years) was significantly less assertive than any of the younger groups of nurses Nurses practising with a diploma as the highest level of education were significantly less assertive than nurses having a baccalaureate or above And there was a significant difference in assertiveness between groups of nurses practising in different clinical specialties based on the ANOVA It appears that the majority of nurses in this study are assertive They believe in themselves and their abilities It is hoped that the self-assertion generated by this belief will eventually lead to further personal and professional empowerment