Background: Vegetarianism has been well known and commonly found in India since ancient times. Animal products provide the only dietary source of vitamin B12. Vegetarianism is a well-known risk factor for vitamin B12 deficiency. The aim of this study to determine the prevalence of vitamin B12 deficiency among vegetarian outpatients, between the age groups of 18 and 60 years, visiting the internal medicine outpatient department of a tertiary level teaching hospital.