Background:Orientation program promote the confidence and competency level of new nurses in providing patient care. Therefore organizations need to support effective orientation programs that are structured to prepare and facilitate the transition of a new nurse to competency. Aim of the study : was to assess the effect of orientation program on competency of newly graduated nurses Subjects and Methods: Research design: A quasi experimental intervention design.Subjects: all the available newly baccalaureate nursing graduates in their first year of practice (n = 60). Setting: Mansoura New General Hospital. Tools of data collection :Two tools were used for data collection: Newly graduated nurses' competency self assessment scale and newly graduated nurses' knowledge test. Results revealed that the majority (90.0%) of newly graduated nurses had average level of competency skills in pre-program self assessment and in observation pre-program, all (100%) newly graduated nurses had low level of competency skills and also in knowledge about competency skills before implementation of the orientation program. However, implementation of the orientation program had a positive effect on newly graduated nurses' level of competency skills' performance and knowledge. Conclusion: Implementation of the orientation program had a positive effect on newly graduated nurses' level of competency skills' performance and knowledge immediately and at three months post-program. Therefore, it is recommended to conduct a well designing effective orientation program for newly graduated nurses based on their competency assessment and knowledge test upon arrival to the clinical setting and careful selection of preceptors and mentors to guide and provide orientation for new graduate nurses is essential.