Objective: American Academy of Pediatrics recommends autism-specific screening at 18 and 24 months of age. This study is a cross-sectional study involving a period of 4 months and investigating the validation and reliability of the Modified Checklist for Autism in Toddlers Test (M-CHAT) and the incidence of autism spectrum disorders (ASD) in our study population. Methods: Four hundred and seventy-one healthy toddlers aged 18-30 months were screened in well-child clinic between June 2017 and September 2017. It was administered to the caregivers by a nurse by face-to-face interview. Screen positive children were reffered to child and adolescent psychiatry clinic for psychiatric evaluation. Results: Of all participants, 264 were boys (56.1%) and 207 girls (43.9%). The mean age was found as 24.5 and 24 months in boys and girls, respectively. The risk of ASD was found as 8/1.000 with the M-CHAT and the incidence was found as 6/1.000 after the psychiatric assessment.We found a sensitivity of 100%; a specificity of 0.95; a positive predictive value of 0.75; and a negative predictive value of 100% and accurate discri-mination rate of 0.96. Cronbachs α reliability coefficient, which was calculated for internal consistency to determine the reliability in the group which underwent the test was found to be 0.96 for the 23 items and 0.98 for the six critical items. Conclusion: M-CHAT is a useful tool in Turkey for screening children for ASD in primary care when adapted to populations with different cultures. [Anadolu Psikiyatri Derg 2019; 20(2.000): 196-203]