The influence of trauma and the mechanical overpull by the strong extensor muscles of the knee are two possible causes of the Osgood-Schlatter's disease. The aim of this study was to assess the relationship between Osgood-Schlatter's disease and the patella alta. The Blackburne and Peel's method of assessing the position of the patella was applied to 144 knees in 94 patients with Osgood-Schlatter's disease. The normal index of 0.84 was confirmed in 65 control knees. In the knees with Osgood-Schlatter's disease the index averaged 1.03(patella alta) in boys and 0.94 in girls(average in whole patients was 1.02) (p<0.05). This finding indicates that the strong pull of the well-developed quadriceps muscle may be a possible etiological factor in patella alta associated with Osgood-Schlatter's disease.