The plasma membranes of erythrocytes derived from Thalassemia major (five cases) and minor (seven cases) were isolated and studied by electron microscopy. It was found that the surface texture of ghosts from all T. minor bloods appeared similar and indistinguishable from ghosts of normal humans blood. The surface texture of ghosts from all T. major bloods likewise were quite similar but distinctly different from T. minor and normal ghosts. These differences were observable whether the specimens for comparison were prepared at the same time or on different days. The results indicate that the morphological characteristics observed in T. major ghosts constitute an expression of an alteration in the molecular structure of their plasma membranes.