Aim of study: To study the effectiveness of balloon blowing exercise on cough strength (Peak cough flow & Maximal Expiratory Pressure) in patients with spinal cord injury. Relevance of the study: Spinal cord injury results in weakness of respiratory and abdominal musculature. Abdominals are required for forceful expiration, paralysis or weakness of these results in impaired cough strength. Balloon blowing exercise are expiratory muscle training exercise which offer resistance against expiration which will improve strength more effectively. To improve strength of respiratory muscles in SCI many studies have been done but there is less evidence on the use of balloon blowing exercise to improve cough strength or expiratory flow rate in SCI. Methodology: The study design was Pre-test and Post-test experimental study which consist of 40 patients with spinal cord injury were selected by convenient sampling. Balloon blowing exercise was given for 4 weeks. Outcome Measure were Peak cough flow (PCF) and Maximal Expiratory Pressure (PEmax). Result and analysis: Pre-Intervention Value of Peak cough flow (PCF) was 242±33.4 L/Min and Post Intervention PCF was 319±36.7 L/Min which shows significant improvement in PCF with p-value <0.05. Pre-Intervention Value of PEmax was 41±5.8CmH2O and post Intervention Value was 48±5CmH2O which shows significant improvement in PEmax with p-value <0.05. Conclusion: This study concluded that balloon blowing exercise improves cough strength (Peak cough flow & maximal expiratory pressure) in spinal cord injury patients. Implications: Balloon blowing exercises can be added as routine physiotherapy treatment as it increases the cough strength and it helps in removing excessive secretions from the lungs. Key words: Peak Cough Flow (PCF), Maximum Expiratory Pressure (PEmax), Spinal Cord Injury (SCI), Balloon Blowing Exercise (BBE)