An alteration of dopaminergic (DA) function much more complex than simple hyperactivity has been evoked in infantile autism. We therefore compared the clinical efficacy of a DA antagonist (amisulpride) and a DA agonist (bromocriptine) in a randomized, double-blind, crossover trial in 9 children with autism, likely severely mentally retarded. Amisulpride acts preferentially on specific autistic symptoms whereas bromocriptine acts more on motor hyperactivity and attention symptoms. These findings raise the specificity of these two drugs which appear to act preferentially on some target symptoms and are consistent with some clinical and pharmacological observations showing a sedative effect with low doses of DA agonists and a stimulant effect with low doses of DA antagonists such as the benzamides.