Atomic Force Microscopy (AFM) is a recent technique that allows evaluation of features in biological systems that could not be previously observed by other instruments. Red Blood Cells (RBC) have been extensively studied because of their relatively simple membrane structure, convenience of preparation and scanning [1]. As an ancillary way of confirming diagnoses, AFM has mostly been used to determine shape and size of RBCs, which are important indicators of some blood diseases or disordered erythropoiesis [2]. In Myelodysplastic Syndrome (MDS) hematopoiesis is inefficacious with consequent anemia that may evolve to acute leukemia. Genomic alterations lead to structural defects in the biomolecular network that forms the erythrocyte membrane. The deformation capability of the cells and their lifetime in circulation are diminished [5]. AFM allows us to observe in a controlled way the response of these membrane molecular networks under physical and chemical stimuli in many different physiological conditions, such as in air and liquids [6]. Using this technique, many new characteristics have been found in erythrocyte membranes that are still of undetermined significance [3,4]. The aim of our work is to compare membrane morphology of two groups of blood donors, that is, healthy subjects and patients with MDS. The images yielded by AFM confirm the structure of the erythrocytes and reveal interesting submicron features on the cell, suggesting a way to distinguish between RBCs from healthy donors and RBCs from patients with MDS.