Cobalamin deficiency is responsible for hematological, neurological, neurocognitive, and neuropsychiatric impairments and is a risk factor for cardiovascular diseases, particularly in the elderly people. In order to determine B12 status in old inpatients, a total number of 14,904 hospitalized patients in whom B12 measurements were performed in five hospitals in the Paris metropolitan area were included from January 1, 2011 to December 31, 2011. The aims of the study were to determine whether age had an impact on B12 and folate deficiencies and to evaluate correlations between B12 and biological parameters-folate, hemoglobin, mean cell volume, homocystein (tHcy)-and age. Patients were aged 70.3±19.5 years. Low B12 concentration (<200ng/L) was observed in 4.6% of cases, 24.2% had middle B12 concentration (200-350ng/L), 12.6% were functional B12 deficient (B12 < 350 ng/L associated to high tHcy level, tHcy > 17 µmol/L), 20.4% had low folate concentration (folate < 4 µg/L), 10.6% were functional folate deficient (folate < 4 µg/L associated to tHcy > 17 µmol/L), and 4.7% of patients were both functional B12 and folate deficient. The B12 or folate deficient patients had lower mean cell volume level than nondeficient patients. Increase in mean cell volume and tHcy concentrations with age and decrease in B12, folate, and hemoglobin levels with age were observed. Frequency of functional B12 deficiency was 9.6% in patients aged 30-60 years and 14.2% in patients over 90 years. Frequency of functional folate deficiency was 9.5% in 30-60 years and 12.1% in >90 years. In inpatients, functional B12 deficiency and functional folate deficiency increase with age and are not associated with anemia or macrocytosis. False vitamin B deficiencies are frequent.