Assessment of nurse instructor critical thinking and their competencies. The aim of the study: was to assess the effect of critical thinking training program on nurse instructors’ competency at Technical Nursing institutes. Subjects & methods: Research design: Aquasi-experimental intervention design was used. Setting:Zagazg university Technical Nursing institutes at Elsharkia Governorate. Subjects: All available nurse instructors. Their total number was 50 nurse instructors. Tools of data collection: A self- administered form including a knowledge questionnaire about reflective thinking and the California Critical Thinking Disposition Inventory (CCTDI), in addition to an observation checklist Results the post-intervention phase showed significant improvements in all areas of knowledge (p<0.001) Slight declines were found in all areas of knowledge at the follow-up phase, but they mostly remained significantly higher compared to pre-intervention phase. Conclusion: a training program in critical thinking is effective in improving their knowledge, and to some extent their performance of teaching role competencies. Recommendations: The curricula of nursing schools and institutions need to be innovated to give more emphasis to critical thinking skills. Further studies are needed for the developed training program should be implemented on a longer period of time, with more emphasis on the application and practice of critical thinking. Keywords: Critical thinking, nurse instructors, teaching, competency