Alexithymia refers to pronounced difficulty in identifying and describing one's own emotions and is associated with an externally oriented focus of thinking. Alexithymia is known to be much more common in adults with autism spectrum disorders (ASD) compared with the typically developing (TD) adult population. However, we know very little about alexithymia in young children with ASD and advancing our understanding of this topic may be of critical clinical and translational importance. Here, we present the first study to examine alexithymia in children with ASD. We find that alexithymia is substantially elevated in ASD on both self‐ and parent‐report measures. Despite both measures being sensitive to on‐average group differentiation, we find no evidence of correlation between such measures, indicating that children and their parents may be using different sources of information. Parent‐rated alexithymia is also associated with increasing levels of autistic traits. Discrepancy between self and other alexithymia ratings are also associated with autistic traits, but only in ASD. These results underscore the idea that assessing alexithymia in ASD at younger ages may help identify important subgroups that have particular difficulties in the domain of emotion processing. Autism Res 2016, 9: 773–780. © 2015 International Society for Autism Research, Wiley Periodicals, Inc.