Objective <p>To compare the effectiveness of segmental breathing exercise and conventional treatment in reduction of duration of mechanical ventilation following coronary artery bypass graft surgery (CABG).</p> Background <p>Bypass grafting of the coronary arteries involves using healthy arteries from the arm, chest, or legs to create a bypass around a blocked artery. Cardiopulmonary bypass surgery, which uses a heart–lung machine, artificially sustains oxygenation and blood circulation. Post-operative pulmonary difficulties from heart–lung machines can result in post-operative morbidity and mortality, which can affect hospital length of stay and health care resources.</p> Methods <p>In a prospective, randomized clinical trial, sixty patients with elective CABG procedures were evaluated at the National Hospital and Medical Centre Lahore. Upon admission, all patients underwent a six-minute walk test (6MWT). A second group was formed by splitting the subjects into two. A respiratory muscle exercise program was conducted by Group I while standard preoperative care was provided by Group 2. 6MWT were repeated the day before surgery (pre-operative) and after discharge (post-operative). Postoperative mechanical ventilation, oxygen therapy, and hospitalization length were recorded as research outcomes.</p> Results <p>According to the pre- and postoperative readings, <i>p</i> value (0.481) indicated interventional group had a better performance on the 6MWT compared to the control group. The <i>p</i> value indicated (0.241) showed shorter postoperative hospital stays, <i>p</i> value 0.205 indicated shorter oxygen therapy duration, and <i>p</i> value 0.001 showed reduced mechanical ventilation duration in the interventional group than in the control group.</p> Conclusion <p>The findings demonstrated that segmental breathing exercise lowers hospital stays and improves postoperative functional capacity.</p>