Although olanzapine is considered to be a safe agent, there are several reports associating it with the development of hyperglycemia, diabetes mellitus (3), and weight gain (4). To our knowledge, olanzapine has not been associated with the development of central or nephrogenic diabetes insipidus. Although schizophrenia has been reported to be associated with polyuria, diabetes insipidus is usually related to lithium therapy and is then of the nephrogenic type. Of note is that olanzapine is chemically related to clozapine, which has been linked to the occurrence of nephrogenic diabetes insipidus (5). We conclude that diabetes insipidus can possibly occur with high doses of olanzapine.