PURPOSE: This study sought to investigate the effects of the McKenzie exercise program on forward head posture and respiratory function. METHODS: Thirty adult men and women with forward head posture, aged 20-29 years, were randomly assigned to the experimental group (N=15) or the control group (N=15). Subjects in the experimental group performed the McKenzie exercises three times a week for four weeks, while subjects in the control group did not receive any intervention. Craniovertebral angle (CVA) was measured to quantify forward head posture, and forced vital capacity (FVC), FVC % predicted, forced expiratory volume at one second (FEV1), and FEV1 % predicted were measured to determine changes in respiratory function. The Mann-Whitney U-test was used to analyze pre-test differences in forward head posture and respiratory function between the two groups, and the Wilcoxon signed-rank test was used to analyze differences in forward head posture and respiratory function within the groups before and after intervention. The significance level (α) was set to 0.05. RESULTS: A comparison of pre- and post-test measures showed that CVA significantly increased in the experimental group (p=0.001) denoting postural improvement, whereas no significant difference was found in the control group (p=0.053). All respiratory measures, i.e.,FVC, FVC %pred, FEV₁, and FEV₁ %pred, were significantly improved in the experimental group, whereas there were no significant differences in the control group. CONCLUSION McKenzie exercise can be effective in improving forward head posture and respiratory function.