Zuclopenthixol acetate is a rapid-acting, injectable neuroleptic drug with a duration of action that allows for administration once every 2 to 3 days, in contrast to injectable haloperidol, which may require administration more than once daily. To assess the place of zuclopenthixol acetate in the treatment of acute episodes of schizophrenia, a cost-consequence analysis was performed comparing this new medication with short-acting, injectable haloperidol. The perspective of the Quebec health care system was adopted. The study population comprised patients diagnosed with schizophrenia who experienced an acute episode of psychosis and who were treated with intramuscular (i.m.) haloperidol. The study assessed patients for 9 days after the start of treatment. The literature was the principal source of comparative data about the clinical outcomes of the two treatments. The total cost associated with zuclopenthixol acetate i.m. or haloperidol i.m. was modeled using a decision tree built around the number of i.m. injections required to achieve stabilization. To establish costs, expert panels were consulted and patients' files were reviewed for a sample of schizophrenic patients who had been hospitalized in a large psychiatric or general hospital subsequent to a visit to the emergency department and had received a short-acting i.m. neuroleptic drug. Only a direct medical records costs were considered. Because zuclopenthixol acetate was not on the market at the time of the study, the file review did not allow for a direct estimate of its related costs but did provide an account of haloperidol use. The literature shows that zuclopenthixol acetate is similar to haloperidol with respect to the control of psychotic episodes; however, zuclopenthixol acetate is associated with increased sedation and a lower incidence of extrapyramidal symptoms. Using the base-case estimate for the number of injections required for stabilization, the incremental cost of zuclopenthixol acetate 50 mg over haloperidol was $25.00 (1995 Canadian dollars) per patient at the psychiatric hospital and $21.00 per patient at the general hospital. The results were sensitive to the estimate of the number of injections and the number of minutes of nursing care required by agitated patients. Zuclopenthixol acetate resulted in cost savings over haloperidol if it permits a reduction of 25% in minutes of nursing care or if 85% of patients require 2 injections or less (45% requiring 1 injection and 40% requiring 2). However, whichever drug is used, the cost of the injectable neuroleptic represents a small fraction of the cost of care for acutely psychotic patients.