Monocytes play a pivotal role in the complex processes of inflammation, immunologic responses and atherothrombosis. Clinical studies essentially reported an increased procoagulant activity in diabetes and coronary disease, suggesting an overexpression of tissue factor. This was further confirmed by the direct measurement of tissue factor on monocyte membrane by flow cytometry. Many receptors can bs measured on monocytes by flow cytometry: beta 2 integrins (CD11a-b-c/CD18) involved in adhesion, EPR-1 receptor, receptors for advanced glycation products, urokinase receptor U-PAR. Flow cytometry allows a cell analysis in whole blood. Modern methods allow a standardization of the procedures and a quantification of the number of sites expressed by the cell. However, the respect of preanalytical and analytical conditions is mandatory to obtain reliable data. Besides, clinical studies in diabetes should carefully define the subgroups of patients: type of diabetes, metabolic abnormalities, risk factors, infective complications (J Mal Vase 1999: 24: 275-280).