Abstract Introduction Clozapine is a well-recognized effective treatment for some patients with treatment-resistant schizophrenia (TRS). Although it has potential benefits and approximately 30% of patients have a clinical indication for clozapine use, prescription rates are low. Objective To evaluate clozapine prescription trends over a 5-year period in a tertiary psychiatric hospital. Methods In this observational study, data prospectively collected by the Medical and Statistical File Service (Serviço de Arquivo Médico e Estatístico) and the Pharmacy Division of Instituto de Psiquiatria de Santa Catarina between January 2010 and December 2014 were summarized and analyzed by investigators blinded to data collection. The number of 100 mg clozapine pills dispensed by the Pharmacy Division to the inpatient units was the outcome and considered a proxy measure of clozapine prescriptions. The number of occupied inpatient unit beds and the number of patients admitted with F20-F29 (ICD-10) diagnoses during the study period were considered to be possible confounders. Results A multiple linear regression model showed that time in months was independently associated with an increase in the number of clozapine pills dispensed by the Pharmacy Division (β coefficient = 15.82; 95% confidence interval 10.88-20.75). Conclusion Clozapine prescriptions were found to have increased during the 5-year period studied, a trend that is opposite to reports from several other countries.