[en] Objective: To explore the clinical significance of changes of serum NO, NOS and plasma ET levels after treatment in children with bronchopneumonia. Methods: The plasma concentrations of ET were determined with radioimmunoassay (RIA) and serum NO, NOS contents were determined with biochemical methods both before and after treatment in 44 children with bronchopneumonia as well as in 35 controls. Results: Before treatment, serum concentrations of NO, NOS and plasma ET levels in the patients were significantly higher than those in controls (P<0.01). After 7 days treatment, the levels of NO, NOS, ET in the patients were not much different from those in the controls (P>0.05). Conclusion: Detection of serum NO, NOS and plasma ET levels were useful for assessment of therapeutic efficacy. (authors)