Since autism was first described by Leo Kanner the view on its etiology and pathogenesis has been changing. Recently there are more data on genetic and neurobiological background of autism. At the beginning it was noticed that autism appeared more frequently among boys, in population studies it was found that autism appeared more frequently among siblings, mostly among monozygotic twins. Many disorders like Tourett syndrome and tuberous sclerosis were reported in connection with autism. Recently research is focused mostly on chromosome abnormalities: chromosome 15 (locus 15q11-13), chromosome 7 (locus 7q), chromosome 16 (locus 16p) and gens of particular receptors (GABRB3, UBE3A/E6-AP, 5-HTT). These abnormalities may also be one of the causes of autism.