Background. The purpose of this study was to determine pediatric nurses’ knowledge of autism spectrum disorders (ASD). Methods. We conducted a population-based online survey of 273 pediatric nurses in eastern Saudi Arabia using convenience sampling method. Perceived knowledge was assessed using the knowledge of childhood autism among Health Professionals Questionnaire (KCAHW) that was translated into Arabic. We used multivariate regression analysis to determine the influence of demographic factors on the perceived knowledge. Using Pearson’s correlation analysis, we assessed the correlation between the outcome variables and the predictor variables. Results. ASD knowledge is generally higher among pediatric nurses with higher academic qualifications (r = 0.29,
p
< 0.001). They scored higher on general knowledge (M = 21.5, SD = 5.7) and lower on signs and symptoms (M = 15.2, SD = 4.3), diagnosis (M = 13.8, SD = 3.9), and management of ASD (M = 12.4, SD = 4.1). A significant correlation was found between mean KCAHW and age (r = 0.12,
p
= 0.029), sex (r = 0.18,
p
= 0.003), years of experience (r = 0.25,
p
< 0.001), education level (r = 0.34,
p
< 0.001), and hospital type (r = 0.21,
p
= 0.001). Predictors of knowledge and understanding were level of education (β = 0.23,
p
= 0.001), formal training (β = 0.16,
p
= 0.012), and years of experience (β = 0.19,
p
= 0.005). The majority could not define ASD or recognize early signs and symptoms or associated comorbidities. Lack of social and emotional reciprocity and impaired language development have been reported, as well as the perception of ASD as a neurodevelopmental disorder. Conclusion. Higher academic qualifications are associated with high general knowledge of ASD; however, nurses in this cohort performed poorly in ASD sign and symptom recognition, diagnosis, and management.