Clozapine represents the treatment of choice for refractory psychosis, although a significant number of individuals demonstrate suboptimal response to it as well, leading to clozapine augmentation strategies. A variety of agents have been investigated in this regard, including mood stabilizers, such as anticonvulsants. Within this group of medications, topiramate is unique in that it is associated with weight loss, making it an attractive option because of clozapine's notable risk for associated metabolic disturbance. A 12-week naturalistic, open study was carried out to examine the potential benefits of topiramate in clozapine-treated individuals with schizophrenia demonstrating a suboptimal clinical response. We were specifically interested in clinical symptoms, changes in metabolic parameters, and tolerability. A total of 20 subjects were enrolled, and 16 completed the study, including 5 individuals with type 2 diabetes. Topiramate augmentation led to a 14% improvement in total Brief Psychiatric Rating Scale scores (P = 0.0003), a 2.5% decrease in body weight (P = 0.015), and was generally well tolerated, paraesthesia being the most common side effect. These findings support topiramate as a viable augmentation strategy in clozapine partial responders, with evidence of both clinical and metabolic benefits.