Association of pernicious anemia and systemic lupus erythematosus is rare, although both diseases are autoimmune origin. We describe the case of a 40-year old man with systemic lupus erythematosus (SLE) who developed pernicious anemia. The cobalamin deficiency was revealed by macrocytic pancytopenia. After 1 month of vitamin B12 treatment, hemoglobin and white blood cell count remain normal but thrombocytopenia persists and was considered as immunologic from SLE origin requiring corticosteroids.