Purpose : Minimal Change Disease (MCD) is the most common primary nephrotic syndrome in children. Some suggested that tumor necrosis $factor-{alpha}$ ($TNF-{alpha}$) are involved in the pathogenesis of MCD. Methods : This study was done to see the changes of plasma and urinary $TNF-{alpha}$, and its effect on the determination of permeability of the glomerular basement membrane (BM) contributed by heparan sulfate proteoglycan (HSPG). Study patients consisted of 19 biopsy-proven MCD children aged 2-15 years old. Both plasma and urinary $TNF-{alpha}$ were measured. Employing the Millicell system, $TNF-{alpha}$ was screened for the permeability factors. We examined whether $TNF-{alpha}$ regulated BM HSPG gene expression and HS synthesis in the glomerular epithelial cells (GECs). Results : Urinary $TNF-{alpha}$ during relapse was significantly increased when compared with that of during remission or controls ($364.4{pm}51.2$ vs $155.3{pm}20.8,;36.0{pm}4.5$ ng/mg cr) (P<0.05). However, negative results were obtained in the permeability assay using the Millicell system. No difference was seen in the BM HSPG gene expression and HS synthesis in the GECs. Conclusion : It seems that $TNF-{alpha}$ may not play a disease-specific role in the pathogenesis of MCD.