An increase in the prevalence of autism spectrum disorders (ASD) in the last few decades has resulted in the enhanced interest of professionals, researchers and the public in this disorder. The newest data indicate that the prevalence rate is more than 1:100. ASD is becoming diagnosed at an earlier age and the standard to strive for is to diagnose children in the preschool period, preferably during the first three years of life. New studies indicate a relatively high reliability of diagnosis if it is made in children whose (mental) age is above 18 months. Since there is still no biomedical marker of ASD, diagnosis is based on behavioral deviations described in diagnostic manuals (DSM or ICD) that have changed often through time. Contemporary studies on aspects of ASD diagnostics – diagnostic criteria and implications of their frequent changes, age for diagnostic assessment, areas and measures of assessment are presented in this paper. Moreover, deficiencies in basic prerequisites for early diagnosis of ASD in Croatia are considered as well as possible implications of this unsustainable system on clinical and research practice in our country.

autism spectrum disorders, ASD, autism, assessment, behavioral characteristics, biomedical characteristics