Background : Staff nurses have interaction with patients , colleagues and other health care specialists on a day by day basis and this interaction is advanced when staff nurses have good communication capabilities . It is far vital for them to be more assertive and have excessive self-efficacy .Aim :To assess assertiveness behavior and self-efficacy among staff nurses at Main Mansoura University Hospital . Subjects and Methods :Descriptive design was used to achieve the aim of the present study . Subjects were included 108 staff nurses working in all medical and surgical departments at Main Mansoura University Hospital . Two tools were used for data collection , first tool was assertiveness assessment scale and the second tool was general self-efficacy scale questionnaire sheet . Results and conclusion : There was a statistical significant positive correlation between assertiveness and self-efficacy. Recommendations : Providing specific courses for enhancing the acquisition of assertiveness skills , rules , techniques and self-efficacy and maintaining continous development activities for staff nurses to improve their feelings , understanding and capabilities of self-efficacy .