High-Dysplastic Developmental Spondylolisthesis (HDDS) is an extremely rare situation, comprising of around 5% of the total cases of spondylolisthesis. Clinical Description :- A eleven year-old girl with high-grade dysplastic L5-S1 spondylolisthesis with pain in her lower back along with radicular pain to her lower limbs (right > left). Her X-rays depicted a L5 - S1 anterolisthesis leading to an abnormal kyphosis at lumbo-sacral junction, increased lumbar lordosis and reversal of thoracic kyphosis to lordosis. Management:- A was done along with a cage insertion at the L5 - S1 level. L5 - S1 posterior - spinal fixation Outcome:- Postural correction was achieved immediately post-op and the patient also had relief from the radicular symptoms.