Cobalamin (vitamin B₁₂) deficiency occurs with several disorders, involving different organs and systems, including blood, bowel, nervous system and eyes. Although the most important features are usually haematological ones, presence of neurological involvement, in the absence of blood count alterations, has just been described in the literature. Here we report the case of a 48-year-old man, suffering from coeliac disease for approximately 5 years, vegetarian, who was admitted to our department, referring dysaesthesia of the left lower limb, decreased libido and erectile dysfunction. Vitamin B₁₂ deficiency was proved, even in the absence of blood count alteration, and treated with a vitamin supplement, resulting in complete remission.