A study was conducted to assess the effectiveness of balloon therapy in promotion of pulmonary function among children with respiratory diseases in selected hospitals, Kanpur,Uttar Pradesh. The researcher adopted quasi experimental, nonequivalent control group pre-test and post-test research design for the study. This study was conducted among children with respiratory diseases between age group of 5 to 10 years in selected U.H.M district hospital and Savitri memorial mother and child care centre. The researcher used purposive sampling technique to select 560 samples, in which 280 were selected as experimental group and another280 were control group. Observational checklist was used to assess the pulmonary function prepared by researcher itself. In experimental group balloon therapy is administer for 3 days10 times. The collected data was analyzed by descriptive and inferential statistics. The results were made on the bases of objectives of the study. In pre-test, experimental group 0% children had no respiratory problem, 63% children had mild respiratory problem,37% had moderate respiratory problem, and 0% had severe respiratory problem. In control group 0% children had no respiratory problem, 47% children had mild respiratory problem, 53% had moderate respiratory problem, and 0% had severe respiratory problem. In post-test 90% children had no respiratory problem, 7% children had mild respiratory problem, 3% had moderate respiratory problem, and 0% had severe respiratory problem. In control group 10% children had no respiratory problem, 83% children had mild respiratory problem, 7% had moderate respiratory problem, and 0% had severe respiratory problem. The paired t-test value 0.003 which is non-significant at t-value 0.05.The unpaired t-test valueis 8.751 which is significant at t-value 0.05 and shows significant association between post-test level of pulmonary function among children with respiratory diseases with their selecteddemographic variables. Hence H1 and H2 hypothesis is accepted. The concluded that balloon therapy is effective in increasing level of pulmonary function and shows significant difference in post-test level of pulmonary function among children with respiratory diseases in experimental group and control group.