Introduction: The Metabolic Syndrome, a collection of five problems namely abdominal obesity, hypertension, hyperglycemia, increased triglyceride and decreased level of HDL cholesterol, greatly increase a person’s risk for stroke, heart attack and diabetes. On other side, vitamin B12 has a great protective role on haematological, neurological and cardiovascular system. Aims: To estimate serum vitamin B12 levels among the patients attending hospital with metabolic syndrome and find out the relation of serum vitamin B12 with the various biochemical parameters of metabolic syndrome patients. Materials and Methods: This cross sectional, observational, case-control, and hospital based study included metabolic syndrome patients as cases and age-sex matched healthy subjects as controls. Weight, height, and hip & waist circumferences and blood pressure were measured in cases and control group. Biochemical parameters such as lipid profiles (total cholesterol, HDL cholesterol, LDL cholesterol, VLDL cholesterol and triglyceride), diabetic profiles (fasting & postprandial glucose and HbA1c) and vitamin B12 levels were assayed in both groups. Results: Enrolled in the study were 100 metabolic syndrome patients and 100 age-sex matched healthy control. In socio-demographic data; weight, BMI, waist circumference and waist-hip ratio were strongly related between two groups. In clinical data analysis, blood pressures (systolic and diastolic) were statistically related between cases and controls. Biochemical parameters i.e. lipid profile (total cholesterol, HDL, LDL, VLDL, triglyceride) and diabetic profile (FBS, PPBS, HbA1c) were recorded and found strong statistical relation between metabolic syndrome patients and controls. The results of vitamin B12 levels of both two groups gave strong statistical significance (in cases, 161.0 ± 97.3 pg/ml; in controls, 312.88 ± 119.7 pg/ml). Conclusion: The present study revealed that there is significant decrease of vitamin B12 level among metabolic syndrome patients when it is compared with normal healthy population.