There is some disagreement in the literature regarding the presence of elevated testosterone concentrations in boys with Autism Spectrum Disorder (ASD). To explore that disagreement, the presence of significant differences in testosterone concentrations in young males with Autism Spectrum Disorder (ASD) and normally developing controls aged 6 yr. to 17 yr. was investigated. A total of 136 young males with ASD and 48 age-matched non-ASD males contributed samples of saliva at a set time and these were assayed for testosterone concentrations. There was no significant difference in testosterone concentrations between the two entire samples. When examined at two-yearly intervals, ASD participants had significantly lower testosterone concentrations at age 12 yr. to 13 yr. and also exhibited relatively homogeneous testosterone concentrations compared to non-ASD participants. These data challenge the 'extreme male brain' hypothesis for ASD and suggest that ASD young males were delayed in their pubertal development and that the developmental variability expected in the wider population was not present.