Purpose. The purpose of this study was to assess the influence of hatha yoga exercises on the shaping of the antero-posterior spinal curvature in first-year students of the University of Physical Education in Katowice who participated in hatha yoga classes. Methods. 72 women and 46 men took part in the study. Hatha yoga classes were held once a week for 90 minutes over a period of 15 weeks. Measurements of the subjects' spines were performed twice, first before the start of the classes and then after all the classes were finished. The students were divided into three groups, the first composed of all the participants in the study, the second of students whom attended the yoga classes and practiced hatha yoga in their free time, whereas the third group was composed of students for whom hatha yoga was their only form of physical exercise. The inclination of the anteroposterior curvature of the spine, i.e. the thoracic kyphosis and lumbar lordosis angles, were measured with a Rippstein plurimeter. Results. The results found that after 15 weeks of yoga, a decrease in the thoracic kyphosis angle (ThKA) and lumbar lordosis angle (LLA) occurred in most of the subjects. Differences between the values of these angles before/after yoga were statistically significant in women (p < 0.001), whereas in men, only a decrease of the thoracic kyphosis angle was statistically significant (p < 0.001). After completing the hatha yoga classes, the majority of students (50-62%) were found to have correct angular values of the thoracic kyphosis and lumbar lordosis when compared to the measurements taken before the start of classes (40-45%). Conclusion. An assessment on the shaping of the anteroposterior curvature of the spine finds that hatha yoga exercises have a positive impact on one's body posture in the sagittal plane.