Objective To analyze the clinical and neuropathological characteristics of subacute combined degeneration (SCD) of the spinal cord. Methods The clinical data were collected in 38 cases of SCD. The serum levels of Vitamin B 12 and folic acid in 34 cases and the serum homocysteine levels in 15 cases were determined. The sural nerves in 4 patients were observed by light and electron microscopes. Results The levels of vitamin B 12 in 25 cases and levels of folic acid in 7 cases were lower than normal value, but the levels of homocysteine in 6 cases were higher than the normal value. Pathological examination showed that there were different degrees of segmental loss of myelin sheaths and axonal degeneration in the peripheral nerves in 4 cases. Conclusion The diagnosis of SCD depends on clinical and laboratory data. The biopsy of the sural nerve shows that the main lesion is the loss of myelin sheaths.