The expressive prosodic abilities of two groups of school-age children with autism spectrum conditions (ASC), Asperger's syndrome (AS) and high-functioning autism (HFA), were compared with those of typically-developing controls. The HFA group showed impairment relative to age-matched controls on all the prosody tasks assessed (affect, sentence-type, contrastive stress, phrasing and imitation) while the AS showed impairment only on phrasing and imitation. Compared with lexically-matched controls, impairment on several tasks (affect, contrastive stress and imitation) was found in the HFA group but little in the AS group (phrasing and imitation). Comparisons between the ASC groups showed considerable differences on prosody skills. Impairment in prosodic skills may therefore be a reliable indicator of autism spectrum subgroups, at least as far as communicative functioning is concerned. There were also significant differences between ASC groups and lexically-matched typically-developing children on expressive language skills, but the incomplete correlation of the prosody results with scores on language tasks suggests that the prosodic differences between the two groups may not all be attributable to the level of language skills. Suggested further research is to investigate the relationship of prosody and language skills in this population more closely, and to develop a prosody test as part of the diagnostic criteria of ASC.