The aim of this study was to investigate the role of adhesion molecules P selectin (CD62P) in the pathogenesis of primary nephrotic syndrome (NS) and its relationship with its different pathological types. The expression of CD62P in renal biopsy tissue and peripheral blood platelets from patients with NS were measured with direct immunofluorescence labelling monoclonal antibody and flow cytometry respectively. The results showed that CD62P was expressed in 140/165 cases with NS (84 8%). Among these patients, renal expression of CD62P was lower in MN and FSGS patients than that in MPGN and MsPGN patients, and even lower in MCD patients. The expression of CD62P in peripheral blood platelets of patients with NS was significantly higher than that in the normal control group( P