Thirty patients with a wide range of sore mouth that led to the diagnosis of iron deficiency in 12 patients, pernicious anemia in 8 patients, combined deficiency of iron and vitamin B12 in 2 patients, and anemia of chronic disease in 8 patients were investigated. The oral signs and symptoms included glossitis, glossodynia, angular cheilitis, recurrent oral ulcer, oral candidosis, diffuse erythematous mucositis, and pale oral mucosa. The values of hemoglobin in 30 patients varied from normal to severe life-threatening levels, but none had developed generalized symptoms sufficiently advanced to arouse suspicions of anemia before they visited the Oral Medicine Clinic. The aim of this paper is to describe a retrospective study of 30 patients with oral changes as the initial manifestation of nutritional deficiency or anemia of chronic diseases. Improved diagnosis and classification of anemia based on the mean and heterogeneity of red cell size will be discussed.