Background: Pneumonia is the highly prevalent cause of children's mortality below five years. Using chest percussion could help in management of pneumonia. Aim: this study aimed to evaluate the effect of chest percussion post nebulizer on respiratory status among infants with pneumonia. Research design: The aim of this study was achieved through utilizing a quasi-experimental research design. Sample: 90 infants with pneumonia were admitted to pediatric in-patient medical department at Minia university hospital for obstetrics and Pediatrics and they were separated into two equal groups (control and study). Tools: A structured interview questionnaire tool which comprising of sociodemographic data and medical data of infants. Respiratory status assessment scale which consist of clinical parameters and bio-physiological parameters. Results: Total Mean score of clinical parameters and physiological measurement for infants with pneumonia was statistically significance improved in study group than the control group after application of chest percussion. Conclusion: Chest percussion application had a meaningful role in improving of respiratory condition among infants with pneumonia. Recommendations: Providing training courses for pediatric nurses about the appropriate technique of chest percussion for infants with pneumonia. Future studies should be planned to enrich further evidence based practices about chest percussion effect for infants suffering from pneumonia.