With measurment of Respiratory Burst Activity (RBA) which is important to bactericidal effect of neutrophil, we have tried to assess whether there would be RBA reducion in nephrotic syndrome(NS) that has frequent bacterial infection. We selected 13 patients diagnosed as nephrotic syndrome by ISKDC classification for this research, 8 were in relapse state, 6 were in remission state(3 were tested in both state). For controls, 13 healthy medical students were selected. We showed RBA by measurment of mean fluoruscence channel(MFC) of neutrophils by flow cytometry using that 2',7'- dichloro-fluoroscein diacetate(DCF-DA) combined oxidizing radical from activated neutrophil turned into autofluoruscence. After mixing 6microL of DCF-DA with 300microL of EDTA whole blood, we gated neutrophils by flow cytometry, and then measured MFC from stimulated neutrophils by PMA and rested neutrophils treated by buffer, respectively, simultaneously. In this study, we showed the ratio of PMA-stimulated MFC to non-stimulated MFC(stimulated MFC/ non-stimulated MFC) to be RBA, and compared NS group with control group, relapse group with remission group, hypercholesterolemia group with control group by RBA. 1) There were no significant differences between control group RBA 5.0+/-2.1 and NS group RBA 3.9+/-1.8(P>0.05). 2) There were significant differences between relapse group RBA 3.1+/-2.4 and remission group RBA 5.0+/-1.7(P<0.05). 3) There were significant differences between hypercholesterolemia group RBA 2.8+/-2.1 and control group RBA 5.0+/-2.1(P<0.05). We concluded that hypercholesterolemia in NS might reduce RBA in neutrophil, and act as a factor which would increase the risk of infection in NS. Differences between relapse and remission groups might be thought to be related with hypercholesterolemia, but needed further study with more samples.