Juvenile spinal osteochondrosis (JSO) affects vertebral endplates and may cause intervertebral discs alterations. The condition is typically related to pain, and weakness and shortening of trunk muscles. Sling suspension therapy (SST) has been shown to reduce lumbar pain effectively. It is, however, unclear whether SST is superior to other treatment methods in reducing pain, correcting posture, and activating trunk stabilizers in JSO. In this study, we intended to compare the effectiveness of two different exercise modalities; Sling Suspension Therapy and Gym Ball Exercise in the treatment of JSO in adolescent girls. A randomised controlled single centre clinical trial was carried out in an inpatient rehabilitation unit at a sanatorium. Forty adolescent girls (age 16.3 ± 0.47 yrs.), who were diagnosed with JSO (according to ICD-10 Version: 2016 - M 42.0) were randomly assigned into two groups: Group 1 - Sling suspension therapy (SST), Group 2 - Gym ball exercises (GBE). Both groups received interventions for 3 weeks, 15 sessions, and 30 minutes a day for 5 consecutive days a week. Back pain, endurance of trunk muscles and standing posture were evaluated pre- and post-interventions. Both groups demonstrated significant improvement in all measured outcomes. SST was more effective in reducing pain (p< 0.05), increasing the endurance of trunk muscles (p< 0.05) and improving the standing posture (p< 0.05) compared to GBE (p< 0.05). Sling suspension therapy is more effective compared with Gym ball exercises in the treatment of juvenile spinal osteochondrosis in adolescent girls in terms of back pain, posture and endurance of trunk muscles.