Background: Communication skills are of major importance in the nursing practice, with important positive impacts on patients’ outcomes and reduce workplace deviance behaviors. Aim: This study aimed at assessing effect of communication skills training program on staff nurses' workplace deviant behavior. Methods: The study was conducted at non critical units of Ain-Shams University Hospital, Cairo, Egypt using quasi-experimental one-group pretest-posttest design. The subjects of this study included all staff nurses who are working at the pre mentioned setting during the data collection period. The study sample was 130 staff nurses, 42 males, and 88 females. The data were collected by using three tools namely; communication skills knowledge questionnaire, observation checklist and nursing workplace deviance behavior questionnaire. Results: The study revealed a highly statistically significant improvement in staff nurses' total knowledge of communication and workplace deviance behaviors in the post and follow up phases p<0.01 as compared to the pre-intervention phase. Also, there was a highly statistically significant improvement in staff nurses' practices of communication in the post and followed up phases p<0.01 as compared to the pre-intervention phase. In addition, there was a highly statistically significant decline in staff nurses' workplace deviant behavior in the post and follows up phases p<0.01 as compared to the preintervention phase. Conclusion: Implementing a communication skills training program for staff nurses is effective to reduce their workplace deviant behavior. Based on the study findings, it was recommended that communication skills training program should be applied in all nursing curricula. Develop and communicate clear policies regarding acceptable behavior and workplace standards.