Autism spectrum disorders (ASD) form a continuum of neurodevelopmental disorders characterized by deficits in communication and reciprocal social interaction, repetitive behaviors, and restricted interests. Sensory disturbances are also frequently reported in clinical and autobiographical accounts. However, few empirical studies have characterized the fundamental features of sensory and multisensory processing in ASD. Recently published studies have shown that children with ASD are able integrate low-level multisensory stimuli, but do so over an enlarged temporal window when compared to typically developing (TD) children. The current study sought to expand upon these previous findings by examining differences in the temporal processing of low-level multisensory stimuli in high-functioning (HFA) and low-functioning (LFA) children with ASD in the context of a simple reaction time task. Contrary to these previous findings, children with both HFA and LFA showed smaller gains in performance under multisensory (i.e., combined visual-auditory) conditions when compared to their TD peers. Additionally, the pattern of performance gains as a function of SOA was similar across groups, suggesting similarities in the temporal processing of these cues that runs counter to previous studies that have shown an enlarged “temporal window.” These findings add complexity to our understanding of the multisensory processing of low-level stimuli in ASD and may hold promise for the development of more sensitive diagnostic measures and improved remediation strategies in autism.