There are no epidemiological data on autism for Mexico. This study was conducted to generate a first estimate of ASD prevalence in Mexico. We surveyed children age eight in Leon (Guanajuato). The sample was stratified in two strata: (1) children having special education and medical records (SEMR; N = 432) and (2) children attending regular schools (GSS; N = 11,684). GSS children were screened with the SRS and those with the highest scores were invited to a diagnostic evaluation. The final sample comprised 36 children (80.6% male) who had confirmed ASD. A third had intellectual disability, 25% were non-verbal, 69% had co-occurring behavioral problems. The prevalence overall was 0.87% (95% CI 0.62, 1.1%). This survey provides an estimate for ASD prevalence in Mexico that is consistent with recent studies.