Autism Spectrum Disorders (ASD) are lifelong neurodevelopmental disabilities. Burden of Disease is an indicator that provides important information on health status and outcomes such as premature mortality and disability. In order to estimate the burden of disease of ASD in the Spanish population during 2003, we followed the procedures used in the WHO Global Burden of Disease Study. ASD generated 43,928 Disability Adjusted Life Years (DALY) in Spain in 2003, from which 33,797 were attributable to Autistic Disorder and 10,131 were caused by Asperger's Disorder and Pervasive Developmental Disorder-Not Otherwise Specified. DALY could be a useful tool for health policy makers for setting health service priorities, allocating available resources effectively and providing a comparable measure of output for early intervention.