In Lebanon, no estimate for autism prevalence exists. This cross-sectional study examines the prevalence of Autism spectrum disorder (ASD) in toddlers in nurseries in Beirut and Mount-Lebanon. The final sample included 998 toddlers (16-48 months) from 177 nurseries. We sent parents the Modified Checklist for Autism in Toddlers (M-CHAT) for screening, and a self-administered questionnaire (associated factors). We imputed missing M-CHAT data with successful answers. Since there were no follow-up interviews for the M-CHAT, we used the positive predictive value (0.058) from a large study for prevalence estimates. ASD prevalence was 1 in 66 children (comparable to US). Ratios were: male/female: 1.05; Beirut/Mount-Lebanon: 1.2. Using a more representative sample and ascertaining results are needed for better prevalence estimates in Lebanon.