question: PURPOSE To evaluate the prevalence of metabolic syndrome (MetS) and its components in adult hypopituitary patients. PATIENTS AND METHODS Retrospective, cross-sectional analysis of a cohort of hypopituitary adult patients followed in a single reference center for pituitary diseases. MetS was defined by the National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) criteria. Patients with 18 years or older, presenting two or more anterior pituitary deficiencies associated or not with diabetes insipidus (DI), were included, while patients with hypopituitarism due to Acromegaly or Cushing's disease were excluded. RESULTS We studied 99 hypopituitary patients (52 males, mean age 50.1 ± 16.3 years, mean age at diagnosis 33.7 ± 17.6 years) who have been followed for a mean time of 15.9 ± 10.1 years. Hypothalamic-pituitary tumors and non-tumoral etiologies were observed in 53.4% and 46.6% of the cases, respectively. FSH/LH, GH, TSH, ACTH deficiency and DI was present in 99%, 98.6%, 96%, 81.8%, and 23.2%, respectively. The prevalence of MetS was 39.4% and was significantly higher in patients older than 50 years (p = 0.02), overweight/obese (p < 0.001), with hypopituitarism diagnosed in adult life (p = 0.02), who did not replace GH (p = 0.004) and in smokers (p = 0.007). In the logistic regression model, body mass index (BMI) and GH replacement were significantly associated with the presence of MetS. Reduced HDL cholesterol was the most prevalent component of MetS in hypopituitary patients. CONCLUSIONS MetS is a common finding in adult hypopituitary patients, which is mainly influenced by increased BMI and untreated GH deficiency. Trial Registration number (Plataforma Brasil): CAAE 51008815.2.0000.0096 (May 31, 2017) .