We present data on the intellectual, language and executive functions of 26 children who had undergone surgery for the removal of cerebellar hemisphere or vermal tumours. The children with right cerebellar tumours presented with disturbances of auditory sequential memory and language processing, whereas those with left cerebellar tumours showed deficits on tests of spatial and visual sequential memory. The vermal lesions led to two profiles: (i) post-surgical mutism, which evolved into speech disorders or language disturbances similar to agrammatism; and (ii) behavioural disturbances ranging from irritability to behaviours reminiscent of autism. These data are consistent with the recently acknowledged role of the cerebellum as a modulator of mental and social functions, and suggest that this role is operative early in childhood.