Introduction: Moral Distress is a serious problem in nursing which contributes to nurses feelings of loss of integrity and dissatisfaction with their work environment.it affects relationships with patients and others and can affect the quality, quantity and cost of nursing care. Methods: In this quasi experimental study, 70 nurses who worked in two Uromia hospitals selected using convenience sampling method. Data were collected with Corley and Hamric Moral Distress scale before and one month after intervention after pretest nurses in the intervention group participated in moral distress workshop and then after each stressful incident, debriefing sessions with seven phases Mitchell's technique were convened several times. One month later two groups completed the questionnaire once again and statistical analysis of data was carried out with SPSS ver.18. Results: Results showed that frequency of moral distress experiences after stressful incident debriefing sessions in the intervention and control groups showed no significant differences.(p=0/448) While intensity of moral distress experiences after stressful incident debriefing sessions in the intervention group showed statistically significant reduction (p<0/001). Conclusion: The results of this study showed that stressful incident debriefing sessions on moral distress effectively alleviates intensity of nursing staff moral distresses.