Abstract BACKGROUND: Psychotic disorders are associated with symptoms such as delusions and hallucinations as well as impaired functioning. Second generation antipsychotic medications are the first line treatment for psychotic disorders, however a proportion of individuals will not respond to the medication. Clozapine is the most effective second generation anti-psychotics, however it is only used as a third line treatment because of serious side-effects. It is associated with metabolic side-effects, which increase the risk of obesity and diabetes mellitus. AIM: Determine the changes in the weight, waist circumference and blood pressure as well as triglycerides, fasting glucose and cholesterol in young people commenced on clozapine after 18 weeks and 6 months of commencement. METHOD: This is a cohort study, including participants aged 15-24 commenced on clozapine between the time period 1st of April 2016 and 30th of September 2017. Data concerning measured outcomes was gathered from patient journals. RESULTS: A total of 36 young people were commenced on clozapine during the study period and the mean age was 19.8 (SD±3.1). At the time of commencing clozapine, the mean weight of the cohort was 86.30kg (±17.08) and after 18 weeks it was 88.90kg (±16.71), and this difference was statistically significant (n=27,df=26,p=0.02) and this weight gain was present for males (n=17,df=16,p=0.038) but not females (n=10,df=9,p=0.214). CONCLUSION: Clozapine may be associated with weight gain in the early stages of commencement and it appears that males are more susceptible to this side-effect. More interventions aimed at attenuating this weight gain is needed.