The prevalence of autism spectrum disorder (ASD) among sub-Saharan African children with intellectual disability is about 0.7% more than three decades ago. During this period, the prevalence of ASD has been on the increase worldwide. Studies are not available in recent times addressing epidemiology of ASD among sub-Saharan African children. The present study assessed the prevalence of ASD among Nigerian children with intellectual disability. Forty four children with intellectual disability were assessed for diagnosis of childhood autism based on criteria specified in F84.0 section of International Classification of Diseases, Tenth Edition (ICD-10) Diagnostic Criteria for Research. Five (11.4%) of the children studied met the diagnostic criteria for childhood autism. Male/female ratio was 4:1. There is need for large scale epidemiological studies of ASD among sub-Saharan African children to clearly define the inter-relationship between ASD and intellectual disability in this population and to help in health care policy formulation.