The main goal of the study was to determine the types of body posture of boys (n = 273), 10 to 13 years of age, by means of the body posture assessment method based on the software Posture Image Analyzer. The results should enable better understanding of postural issues, as well as timely and more precise selection of kinesitherapeutic procedures. Values of 5 front view and 4 sagittal view indicators of standing body posture were measured by means of subjects' photographs and software Image Posture Analyzer Cluster analysis (K-means method) revealed three types of body posture in both the anterior and sagittal plane. Their characteristics were determined with discriminant analysis. In sagittal indicators three posture types are recognizable: (a) correct sagittal body posture (29.3%), (b) mild impaired sagittal body posture (41.8%), (c) marked impaired sagittal body posture (28.9%). In anterior indicators also three posture types are recognizable: (a) correct anterior body posture (19.4%), (b) mild scoliotic body posture in the lumbar region (47.6%), (c) mild scoliotic body posture with double curvature (33%).