Autism is a complex neurological developmental disorder with wide range of symptoms. Among them, poor social interaction, limited and repeated behavioral patterns are the most important for diagnosing the disorder. The prevalence of autism is rising constantly. One of the theories drawing the greatest public attention for a long time is a possible association between MMR vaccine and risk of autism. The first study aimed to investigate this association is the one conducted in 1998. As the results supported the theory that MMR vaccine increased the risk of autism, MMR immunization coverage decreased dramatically which further led to measles outbreaks, even in those countries where the disease was almost eradicated. Soon after that publication, new studies denying any association between MMR vaccine and risk of autism were published. Among them, systematic review published in 2012, including 57 epidemiological studies with 14.700.000 children is particularly important. Although the etiology of autism is not completely clarified, there are strong evidence on the presence of neurobiological changes with significant genetic component underlying the etiology. According to recent literature data, morphological changes in brain of children age 6 to 12 months, that is, before the administration of MMR vaccine, precede clinical symptoms of autism.