Neurological disorders related to vitamin B12 deficiency are common in prisons of tropical Africa. We collected 22 cases (20 men and 2 women). They all showed vitamin B12 deficiency associated with neurological signs that were represented by sclerosis combined with bone marrow (n = 9), peripheral neuropathy (n = 6), cerebellar syndrome (n = 2), a pyramidal syndrome of the lower limbs (n = 4) and optic neuropathy (n = 1). Laboratory tests showed a mean hemoglobin concentration of 7.2 ± 1.5 g/dl, mean 104 ± 28 fl, macrocytic anemia in 10 patients. Biermer's disease was identified in 9 patients, 3 patients showed the syndrome of non dissociation of vitamin B12, a gastrectomy in 2 patients and no etiology was identified in 8 patients.