In our study we evaluated erythrocytic morphology in different pathologies which can modify flowing red cells. We followed the methodology proposed by Zipursky which allows a three-dimensional evaluation of the red cell and a classification according to the shapes observed through the optical microscope. We studied 150 subjects: 20 normal subjects, 58 patients suffering from vascular diseases, 40 affected by diabetes (type II) (10 without and 30 with vascular diseases), 22 patients with liver disease, 5 patients with monoclonal gammopathies and 5 dehydrated patients. Results show that in normal subjects bowls, which is the shape of the most deformable red cells, are more (55%) than discocytes (44%); the altered forms are only 1%. In vascular patients we noted a statistically significant increase of discocytes (60%). There are no significant differences between subjects affected by diabetes without vascular disease and normal subjects. In diabetics with vascular diseases there are more discocytes (57%) and some altered forms (3%). In patients suffering from chronic hepatitis a great increase (13%) in echinocytes and knizocytes was noticed, which suggests an alteration in the fluidity of the membrane. Our observations testify the importance of this simple methodology in focusing the morphological alterations which can be accounted for both by pathologies of the red cells and by changes in their metabolism.