It has been suggested that the deficit in understanding others' intention in autism depends on a malfunctioning of the mirror system. This malfunction could be due either to a deficit of the basic mirror mechanism or to a disorganization of chained action organization on which the mirror understanding of others' intention is based. Here we tested this last hypothesis investigating the kinematics of intentional actions. Children with autism and typically developing children (TD) were asked to execute two actions consisting each of three motor acts: the first was identical in both actions while the last varied for its difficulty. The result showed that, unlike in TD children, in children with autism the kinematics of the first motor act was not modulated by the task difficulty. This finding strongly supports the notion that children with autism have a deficit in chaining motor acts into a global action.