This case is one of several to suggest that atypical antipsychotic drugs as a group may share the potential of uncovering or increasing obsessive-compulsive symptoms in patients with schizophrenia or with schizophrenia and comorbid OCD. We undertook the present trial on the basis of a controlled clinical investigation suggesting that olanzapine, despite its pharmacologic resemblance to clozapine and risperidone (i.e., 5-HT2 antagonism), did not show an association with the emergence of obsessive or compulsive symptoms in patients with schizophrenia (3). All patients in this trial had either no or slight obsessions or compulsions at baseline (i.e., before olanzapine treatment). Therefore, there may be a biological predisposition to developing atypical antipsychotic drug-induced obsessions or compulsions, and this may be prominent in schizophrenic patients with comorbid OCD or in schizophrenic patients with a strong obsessional component. Finally, this report highlights the significance (to the patient) of unrecognized negative or dysphoric symptoms related to use of typical antipsychotic drugs. Although Mr. A did not complain of classic extrapyramidal symptoms or akathisia or have obvious parkinsonian symptoms, he had a fairly robust subjective feeling of improvement and general well-being following discontinuation of haloperidol.