Autism constitutes one of the most investigated disorders in child psychiatry. The heterogeneous clinical phenomena that characterize it have been exhaustibly described along the last 62 years. Multiple aetiological hypothesis, neuropsychological theories and physiopathological mechanisms, sometimes complementary and other times mutually exclusive, and different descriptions of neurobiological alterations that resulted, in general, of low replicability, have attempted to account for the marked variability of its manifestations. An integration of these different levels of analysis results even harder than the comprehension of each of them separately. In this article the author revises the three aspects considered the most characteristic of the syndrome (social interaction, communication and flexibility) and tries to integrate its clinical manifestations with some neuropsychological variables and the neurobiological substrates.