Background: Subacute combined degeneration is a clinical manifestation of vitamin B12 deficiency, that we observe with unusual frequency. Aim: To report a series of eleven patients with subacute combined degeneration. Patients and methods: Retrospective analysis of 11 patients hospitalized in a public hospital in Santiago, between March 2001 and February 2003. All had a myelopathy of more than three weeks of evolution with serum vitamin B12 levels of less than 200 pg/ml. Results: A risk factor was identified in 10 cases and the most common was an age over 60 years old. The main presenting symptom was the presence of paresthesias. On admission, sphincter dysfunction, posterior column and pyramidal syndromes coexisted in nine patients. A level of sensitive deficit was detected in six. Ten patients had macrocytosis and eight were anemic. Serum vitamin B12 was measured in ten and in nine, it was below 200 pg/ml. The mean lapse between onset of symptoms and treatment was eight months. All received intramuscular vitamin B12 in doses on 1,000 to 10,000 IU/day. Sphincter dysfunction and propioception were the first symptoms to improve. Conclusions: Subacute combined degeneration must be suspected in patients older than 60 years with a subacute myelopathic syndrome and low serum vitamin B12 levels