Abstract: OBJECTIVE To investigate the current status of nosocomial infections in hospitalized children with malignant tumor and analyze the direct economic loss. METHODS The children with malignant tumor who were treated in a three-A hospital of Jiangsu province from Jan 1, 2013 to Dec 31, 2014 were recruited as the study objects.On the basis of the survey of prevalence of infections, a case-control study was conducted to analyze the direct economic loss due to the nosocomial infections. RESULTS Of totally 717 children who were enrolled in the study, 107 had nosocomial infections for more than 1 time during the hospital stay, 125 case-times of patients had nosocomial infections, with the case-time infection rate 17.43%.There were significant differences in the constituent ratios of nosocomial infection sites between the hematologic tumor infection group and the solid tumor infection group (χ²=27.154,P=0.007).The median of total hospitalization cost of the hematologic tumor infection group was 50108.80 yuan, the hospitalization duration was (6.32±14.08)days; the median of the total hospitalization cost of the non-infection group was 20424.71 yuan, the hospitalization duration was (15.89±9.13 )days.The median of the total hospitalization cost of the solid tumor infection group was 18972.75 yuan, the hospitalization duration was (21.36±9.00) days; the median of total hospitalization cost of the non-infection group was 8985.46 yuan, the hospitalization duration was (15.43±7.38) days; there were significant differences in the hospitalization cost and hospitalization duration between the infection group and the control group (P＜0.05). CONCLUSION The incidence of nosocomial infection is high in the children with malignant tumor.The children with hematologic tumor are at higher risk of infections than the children with solid tumor, and there are significant differences in the nosocomial infection sites between the two.The nosocomial infection may lead to the increase of hospitalization cost and extension of hospitalization duration, with the direct economic loss great.