Objectives: The present study aims to evaluate the serum cobalamin inHelicobacter pylori (H. pylori) infected patients. Study Design: Case control study. Place andDuration: Department of Medicine, Isra University Hospital Hyderabad from March 2013- April2014. Methodology: A sample of 109 subjects including Helicobacter pylori positive subjectsand controls were selected according to study criteria. Centrifugation of blood was performedat 4000 rpm for 10 minutes and sera were stored at -20oC. Blood sera were used for H. pyloriserological testing. Blood counting was performed on hematoanalyzer. Cobas e411 analyzerwas used for detection of cobalamin. 64 kD H. pylori antigens was detected by ELISA. Thedata was entered into SPSS version 21.0. (IBM, Incorporation, USA) A 2-tailed p-value of ≤0.05was considered significant for statistical analysis. Results: Of total 109, 54.1% (n=59) wereH. pylori seropositive cases and others were controls i.e. 45.9% (n=50). Cases and controlsshowed cobalamin levels of 290±49.3 vs. 351±32.9 pg/ml respectively (p=0.0001). Red bloodcell indices were found to show statistically significant difference between cases and controls(p=0.001). Conclusion: Serum cobalamin deficiency was noted in both Helicobacter pyloripositive and controls, however deficiency was more pronounced in Helicobacter pylori positivesubjects.