We observed increased numbers of an infrequently referenced poikilocyte, the prekeratocyte, in iron deficiency anemia (IDA) compared with beta-thalassemia minor and anemia of chronic disease (ACD) and, therefore, chose to quantify these cells and other morphologic features in these anemias. Prekeratocytes were observed in 31 (78%) of 40 IDAs vs 11 (37%) of 30 beta-thalassemias (P = .001) and 5 (13%) of 40 ACDs (P < .001) and averaged 0.78 per 1,000 RBCs in IDA vs 0.21 in beta-thalassemia (P < .001) and 0.075 in ACD (P < .001). Pencil cells also were more commonly seen and more numerous in IDAs than in beta-thalassemia or ACD. Target cells were present in most IDAs and thalassemia and in similar numbers. Basophilic stippling was seen in only 5 (17%) of the beta-thalassemias. Our results lend quantitative support to prekeratocytes and pencil cells as morphologic features favoring the diagnosis of IDA but fail to support the diagnostic usefulness of target cells and basophilic stippling in discriminating IDA and beta-thalassemia minor.