Abstract: Problems of inattention and hyperactivity affect one half of individuals with autistic disorder. Care must be taken to ensure that inattention and hyperactivity are not manifestations of other behavioural pathology seen in association with autistic disorder, as this will affect treatment decisions. The prescribing of psychotropic agents to individuals with autistic disorder is increasing but the evidence base is limited, with some exceptions, to uncontrolled studies. Substantial benefit in reducing inattention and hyperactivity is seen with atypical antipsychotics such as risperidone and quetiapine, although weight gain and sedation are common side effects. Moderate benefit is derived from methylphenidate, atomoxetine, some anticonvulsant medications, guanfacine and donepezil. Data show dexamphetamine, clonidine, clomipramine, mirtazapine, and fluoxetine are of unlikely benefit.