Background:Metabolic syndrome (MetS) is a term used to describe the combination of risk factors including: abdominal obesity, elevated blood pressure, elevated fasting blood sugar, and dyslipidemia that increase the risk for both cardiovascular problems and/or type 2 diabetes mellitus (DM). Several expert groups proposed diagnostic criteria for MetS: these include National Cholesterol Education Program’s Adult Treatment Panel III (NCEP/ATP III) and the International Diabetes Federation (IDF) definitions. Objectives:To estimate the prevalence of MetS in obese and overweight adults (18- 65) living in 3 UNRWA refugee camps in West Bank – Palestine; by both the NCEP/ATP III and IDF definitions. And to find any associated socioeconomic or lifestyle factors linked to MetS. Methods and materials:This is a cross-sectional study that included 689 apparently healthy adults residing in UNRWA refugee camps. The participants were chosen from the attendees of UNRWA clinics in the refugee camps. Data were collected by interviews and anthropometric measurements, overweight or obese adults were offered to perform blood tests including fasting blood sugar (FBS), Triglyceride (TG), and High Density Lipoprotein (HDL). Mets was defined according to NCEP/ATP III and IDF criteria Results:The prevalence of MetS was 52.1% (51.9% men, 52.2% women) according to NCEP/ATP III, and 69.4% (71.8% men, 67.6% women) according to IDF in obese and overweight individuals. The prevalence of MetS increased with age according to both definitions. Physical activity was found to be significantly inversely associated with MetS prevalence according to NCEP/ATP III but not IDF. While no significant associations were found with gender, smoking, TV watching, and family history of hypertension (HTN) or Diabetes Mellitus (DM). Conclusion: MetS is highly prevalent in obese and overweight refugee camp residents, and its risk may decrease with increasing physical activity.This may promote for a national awareness of the benefit of physical activity in decreasing the risk of MetS and thus the risk of cardiovascular complications.