Aim: to assess knowledge and awareness of autism among family medicine residents in King Fahd Medical City “KFMC” in Riyadh Region in Saudi Arabia. Methods: A descriptive cross-sectional study among all family Medicine residents in KFMC-Riyadh using knowledge about childhood autism among health workers (KCAHW) questionnaire. Results: 116 residents’ doctors participate in the study with 66 (56.9%) males and 50 (43.1%) females. Of all participants 17 (14.7%) attended workshops or conferences about autism. The total mean score on the questionnaire among the participants was 12.35 ± 3.6, with a total of 80 (68.9%) of the participants scoring within and above the total mean score. Conclusion: Knowledge of family medicine residents regarding childhood autism spectrum disorder is moderate, and it is mandatory to update the awareness and train them to provide healthcare services that would ensure early diagnosis and proper management of these cases. Keywords: Autism spectrum disorder – awareness – knowledge - family medicine.