Background: Inclusion system refers to the size of an education system to provide the academic and behavioral sustenance needed for all students, regardless of their disability or difference as gender, ethnicity, location, language, to participate and succeed in the academic, social, and extra-curricular activities of the school alongside their lords. Aim: This study aimed to assess teachers' knowledge, practice and attitude toward inclusion system in primary schools. Study design: Descriptive research design was used in this study. Sample: Convenient sample included 200 teachers in primary school for inclusion system in Ismailia city. Setting: 48 governmental primary school for inclusion system in Ismailia city. Tools for data collection: One tool, 1st tool Interview questionnaire included four parts, 1st part: Socio-demographic characteristic, 2nd part: Teachers' knowledge related to inclusion system, 3rd part: Teachers' reported practice, and 4th part: Attitude rating scale to assess teachers' attitudes toward students with disabilities. Results: 5.0 % of studied teacher had good total knowledge. While, 89.0 % of them had unsatisfactory total reported practice, while, 13.0 % of them had positive total attitude. Conclusion: Most of the study teacher had poor total knowledge about the inclusion system, most of them had satisfactory total practice regarding inclusion system and majority of the studied sample had positive attitude about the inclusion system. There is statistically significant relation between teachers' sociodemographic data and their total knowledge, total practice, total attitude regarding inclusion system. Recommendations: Designs health education program to teachers about inclusion system in primary schools.