Diagnostic reports for 206 children who underwent an assessment for autism spectrum disorder (ASD) using the DSM-IV-TR criteria, were re-evaluated using the DSM-5 criteria. Mean age of the children at time of diagnosis was 3 years 10 months. Of the 202 children diagnosed with ASD on the DSM-IV-TR, 184 (91.1%) also met the DSM-5 criteria for ASD. The overall concordance rate of ASD diagnosis on the DSM-IV-TR and DSM-5 was higher than that reported in other studies. Of the 18 children who did not meet DSM-5 criteria for ASD, 16 children met all social communication criteria but did not fulfil at least two restricted and repetitive behaviour (RRB) criteria. Six of those children had further RRBs emerging later on follow-up.