Schizophrenia is a major cause of suicide, and symptoms characteristic of treatment-resistant disease are strong risk factors. Clozapine reduces symptoms in 60% of such patients and significantly decreases the risk of suicide. To model the impact of increased clozapine prescribing on lives saved and resource utilisation. A model was built to compare current levels of clozapine prescribing with a scenario in which all suitable patients with treatment-resistant schizophrenia received clozapine. It was estimated that an average of 53 lives could be saved in the UK each year. If clozapine is cost-neutral, the cost per life-year saved is pound 5108. If clozapine achieves a 10% reduction in annual support costs, the net saving is pound 8.7 million per annum. An average of 167 acute beds would be freed each year. The use of clozapine in treatment-resistant schizophrenia saves lives, frees resources and is cost-effective.