Abstract: Objective: To explore the incidence of infection of primary nephrotic syndrome in childhood and the related factors.Methods: The clinical data of 133 cases hospitalized for primary nephrotic syndrome in our department(from 1997 to 2003) were analyzed.Results: Of the 133 cases of primary nephrotic syndrome,20 were complicated with nosocomial infection and 84 with community infection.Most of the infections occurred in the respiratory tract.The incidence of complication was about 40% when the length of hospital stay was over 3 weeks.Children under 3 years of age were more easily affected by nosocomial infection(P>0.05).Nosocomial infection was related to the decrease of the gammaglobulin level(P<0.01).Country children were more likely to be affected by community infection(P<0.01).Conclusions: Primary nephrotic syndrome tends to be complicated with infections,especially the respiratory infection.High incidence of infection,long length of hospital stay and low level of gammaglobulin are the risk factors.