Background: Autism is a neurodevelopmental disorder that affects communication, behavior, and social interaction. Autism’s estimated prevalence among children was about a 15% percent increase in incidence .Positive teacher attitudes are a vital indicator of the successful education of autistic children. The current study aimed to assess the knowledge and opinions of elementary school teachers toward integrating autistic children in their regular classrooms. Methodology: a descriptive cross-sectional correlational survey research design was used to include 79 elementary school teachers recruited conveniently from two schools located in Jeddah, Saudi Arabia. Two reliable and valid tools were used including autism knowledge and opinion scale in addition to behavioral strategies used by the teachers when they are handling autistic children. Findings: The mean age of respondents were 29.2 years, 86.1% having a bachelor's degree, and only 41.8% having training and experience with ASD. Most respondents 82, 3% had poor knowledge, compared with only 2.5% had good knowledge. Only 40.5% had positive opinions about ASD integration. Additionally, there is no significant association between the demographic background of the respondents, their knowledge and opinions except for their teaching experiences at P≥0.05. Conclusion: The present study concluded and highlighted the inadequate knowledge level of ASD and unfavorable opinions of teachers toward integrating autistic children due to lack of training and attending workshops to improve their qualifications. Therefore, more efforts are required to further enhance the understanding of autism among all teachers who handling those students who are urgently needed.