In patients with drepanocytemia (DP) in basal state and with crises of painful vaso-occlusive (PVOC) authors studied the expression in mononuclear cells (MNC) and neutrophils, of LFA-1, VLA-4, L-selectine and ICAM-1; in peripheral blood (PB), VCAM-1 and CD34 molecules, and in red blood cells with different density, VLA-4 and Lutheran molecules, with specific monoclonal antibodies by indirect immunofluorescence by flux cytometry. In both groups there was a significant decrease in expression of LFA-1 and VLA-4 molecules MNC and of LFA-1 in neutrophils of patients basal state; decrease in L-selectine molecule expression in MNC and in patients in basal state. Increase of IACM-1 (CD54), CD34 and VCAM-1 (CD106) in MNC and in peripheral blood of basal patients shows the presence of a permanent leukocyte activation state determined by the continuous subclinical inflammation. The significant increase of ICAM-1 in neutrophils and CD34 and VCAM-1 in peripheral blood in both groups of patients with a higher increase of VCAM-1 in patients in crises, shows the monocyte, lymphocyte , neutrophils, and of endothelial cells during the PVOC and the release of these latter to periphery. We note a higher expression of LFA-1, L-selectine and ICAM-1 molecules in neutrophils of patients with PVOC and a significant increase of CD18 molecule in MNC of patients with PVOC that may be explained by monocyte activation in vaso-occlusive phenomenon.