Studies have shown that the metabolic syndrome (MetS), a major risk factor for the development of Type 2 diabetes mellitus and cardiovascular disease, is higher among psychiatric patients on antipsychotic medications than the general population. While studies on the prevalence of MetS in the Jamaican adult population have been undertaken, no such study has been done on the corresponding psychiatric population. The purpose of this study was to determine the prevalence of MetS in a Jamaican adult psychiatric inpatient population. The study group comprised thirty-eight patients with a primary DSMIV-TR Axis 1 diagnosis. Criteria for the diagnosis of MetS were the presence of any three or more of five factors as defined by using the International Diabetes Federation (IDF) and American Heart Association/National Heart Lung and Blood Institute (AHA/NHLBI) consensus agreement. The prevalence of MetS in this cohort was 28.9% and was associated with significantly higher abdominal obesity (p = 0.010), elevated blood pressure (p = 0.000), elevated triglycerides (p = 0.019) and low high density lipoprotein-cholesterol (p = 0.016) when compared with patients not diagnosed with MetS. Metabolic syndrome was common in this group of psychiatric patients and likely represents a pathway to the future development of Type 2 diabetes mellitus and cardiovascular disease. Screening and continuous monitoring will allow for early intervention and possibly prevention of increased morbidity and mortality in this vulnerable population.