Assertiveness is the expression of one's feelings, beliefs, opinions, needs in a direct, honest and appropriate manner. Assertive not describe individual only also describe behavior, so that assertive behavior is a behavior which directly expresses individual's true, basic feelings, needs, desires, opinions and personal rights in a positive, productive way without denying the rights of others . The aim of the study: Identifying the factors affecting assertive behaviour among head nurses at Minia University Hospitals. Research design: Descriptive research design was used in this study. Setting: This study was carried out at Minia University Hospitals. Sample: Convenient sample of all available head nurses in Minia University Hospitals with total number (n= 50).Tool: Self–administrated questionnaire sheet which was consisted of two parts: Part (1): Demographic data &Part (II): Factors affecting Assertive Behaviour Questionnaire. Results: Two thirds of head nurses have high assertive behaviour regarding to communication domain but they have low assertiveness in other domains. There were statistical significance difference between communication, rights and responsibilities, and assertiveness as a total and female gender. Conclusions: This study concluded that all head nurses had low assertiveness level. There were no statistical significance differences between head nurses' assertiveness and their socio-demographic Recommendation: Study other factors affecting assertive behaviour such as personality, experience, attitude and beliefs. Further researches to investigate the socio cultural circumstances that may hinder or enhance the individual to be assertive.