BACKGROUND : This study aimed to report the case of a patient who presented with depression, cognitive impairment, ataxic gait, and urinary incontinence associated with vitamin B12 deficiency. METHODS : Serum vitamin B12 level was low in this patient, and anti-intrinsic factor antibody was positive. Neuroimaging revealed abnormal hyperintense signals in the cerebellum and dorsal and lateral columns of the spinal cord, and obstructive hydrocephalus. A biopsy of the stomach revealed chronic gastritis, intestinal metaplasia, and atrophy. After 3 months of initiating methylcobalamin therapy, significant improvement was noticed clinically, and brain magnetic resonance imaging was near to normal. CONCLUSIONS : This study was novel in reporting subacute combined degeneration of the spinal cord and hydrocephalus associated with vitamin B12 deficiency in adults.