Objective: In our study, we aimed to evaluate vitamin B12 deficiency anemia, macrocytosis rate and vitamin B12 values in patients over 65 years of age and compare them with those under 65 years of age.groups. Methods: Retrospectively, A total of 8062 patients, 1213 over the age of 65 and 6849 under the age of 65, admitted between March 2019 and March 2024 were included in the study. The patients' hemoglobin, hematocrit, MCV, White blood cell (WBC), Red cell distribution width (RDW), Platelet (PLT) values and vitamin B12 levels were examined. Patients were divided into two groups as age of 65 and over and age below 65, and each group were divided into two groups in terms of anemia. Groups and subgropus were compared with each other Results: While the ratio of vitamin b12 deficiency anemia in patients over 65 years of age was 20.2%, the ratio of anemia in patients under 65 years of age was 8.3%. It was observed that there was no significant difference in vitamin B12 levels in terms of gender in both age groups. With the roc analyses the cut-off value for vitamin B12 causing anemia in patients over 65 years of age was 327 pg/mL (AUC: 0.602, p≤0.001) with a sensitivity of 94.3% and specificity of 34.2%. Conclusion: The fact that vitamin B12 levels that cause anemia in elderly patients are higher than in young-adult patients made us think that the usual limit values may need to be reconsiderated in geriatric population