Objective: The purpose of this study was to examine the effect on vital capacity (VC) and inspiratory muscle activation according to the anterior and posterior pelvic tilt positions. Design: One group pretest-posttest design. Methods: Twenty-six healthy adult men and women, age 19 to 27 years, volunteered to participate in this study. Forced vital capacity (FVC), and forced expiratory volume in 1 second (FEV1) were measured by desktop spirometer in the pelvic positions during respiration, and muscle activation was recorded from sternocleidomastoid, upper trapezius, external intercostal, rectus abdominis, and external oblique muscles by surface electromyography (EMG) at the same time. EMG values were normalized by maximum muscle contractions (% maximum voluntary isometric contraction). Subjects were to breathe in as much air as possible and then exhale as quickly as possible in both anterior and posterior pelvic tilt positions. To measure lung capacity, inspiration was measured for 5 seconds and expiration was measured for 7 seconds with data collection taken place during the middle three seconds. Lung capacities were measured in each position three times. Results: For the results of this study, there was a significant increase in both FVC and FEV1 values during the anterior pelvic tilting compared to the posterior pelvic tilting posture (p<0.05). The sternocleidomastoid, upper trapezius muscle, rectus abdominus and external oblique muscle activation was significantly increased during anterior pelvic tilt compared to the posterior pelvic tilt position (p<0.05). Conclusions: These findings suggest that pelvic anterior tilt position could be more effective for vital capacity and respiratory muscles activation during respiration.