Background: The transition period is a time for learning, adjusting, and socializing, in which the novice nurses apply, consolidate, and expand upon the knowledge already acquired. This study aimed to determine the effect of transitional training program on knowledge and experience of novice nurses' role transition in critical care units at Alexandria Main University Hospital. Research design: A quasi-experimental, interventional research design was utilized. Setting: The study was conducted in critical care units, at Alexandria Main University Hospital. Subjects: All nurses with less than one year of working experience were included. (N = 72). Tools: The study's tools involved role transition knowledge questionnaire which composed of 50 questions and the Casey-Fink Graduate Nurse Experience Survey, which contained 37 questions, which were used pre, immediately after, and following three months of transition experience. Results: The transition training program had a significant positive impact on novice nurses' knowledge and experience. Conclusion: The current study revealed a significant positive correlation between novice nurses' overall role transition knowledge and experience at various stages of the transition training program. Recommendations: Hospital administrators should conduct a continuous role transition training programs for all novice nurses.