Leukopenia and neutropenia are recognised as side effects of antipsychotic medication, notably clozapine. A case is presented in which a female Caucasian patient who had previously developed these side effects with clozapine also developed them with quetiapine in conjunction with semisodium valproate. There was no such reaction to zuclopenthixol, sulpiride, olanzapine and aripiprazole. It is concluded that caution should be exercised when treating with quetiapine especially where there has been neutropenia with a previous antipsychotic agent.