Haloperidol is commonly used in therapy for patients with acute and chronic schizophrenia. Because it can have some adverse effects on specific target organs such as the liver, we analyzed whether haloperidol exerts a toxic effect on rat liver by means of stereological and histopathological methods. Fifteen adult male rats, divided into three groups, were used in the experiments. Once a day for 6 weeks, either saline or 0.4 or 0.8 mg kg(-1) doses of haloperidol were given interperitoneally to the control, low-dose, and high-dose groups, respectively. At the end of the experiment, rats were killed by an overdose of a general anesthetic, and the livers were dissected out, fixed for sectioning, and evaluated using stereological and histopathological methods. Hepatocyte numbers were found to be 271.672, 291.072, and 238.415 hepatocytes per cubic millimeter in the liver of the control, low-dose, and high-dose groups, respectively. The differences between high-dose and control groups and also between high-dose and low-dose groups were significant (p < 0.05). Our histopathological findings at both the structural and the ultra-structural level were confirmed by stereological estimations. Results suggest a relationship between haloperidol dose and toxic effects on the liver, and they indicate that a high dose of haloperidol may result in irreversible liver damage.