Evidence suggests that individuals with autism spectrum disorders (ASD) exhibit difficulty in integrating crossmodal information. The present study investigates whether children with ASD have difficulty in crossmodal processing across auditory and visual modalities.We observed 10 children with ASD and 11 IQ-, age-, and gender-matched, healthy, control children. In the visual-only gap/overlap task, children with ASD exhibited the same performance as control children. In contrast, in the audio-visual condition, children with ASD were significantly slower to respond than control children in both the gap and overlap tasks. In addition, the gap effects between the ASD and control groups were observed in each condition, but no significant group differences were observed. These results suggest that children with ASD exhibit difficulty in simultaneously allocating attentional resources to auditory and visual modalities although children with ASD are intact in disengagement of attention.