Objective: To find the effect of aerobic exercises versus respiratory muscle training on lung function among quarry workers (Randomized controlled trial). Forty quarry workers participated in the study. Methods: Patients were randomly allocated to two groups. Group A was given aerobic exercises by engaging in a 30 minute session of walking on a treadmill for eight weeks, three times a week (control group). Group B was given a respiratory muscle training program using an incentive spirometer, diaphragmatic breathing exercises, lateral costal breathing exercises, and pursed lip breathing exercises in addition to aerobic exercise for eight weeks (study group). A spirometer was used for a pulmonary function test, which evaluated lung function by measuring Forced Vital Capacity (FVC), Forced Expiratory Volume in one second (FEV1), and the ratio of FEV1 to FVC. Results: Findings of this study indicated substantial improvements of FVC, FEV1, and FEV1/FVC after treatment in both groups values (P value < 0.00001). There were significant differences between both groups after treatment regarding FVC, FEV1, and FEV1/FVC, with favored results in Group B. Conclusion: Both groups showed a significant improvement in lung function in favor of group B. So, this study proves that respiratory muscle training is an essential supplement to aerobic exercise for pulmonary rehabilitation to improve pulmonary functions in quarry workers.