A pathogenetic mechanism of the idiopathic scoliosis (IS) has been established on the basis of in-depth morphological and biochemical investigations of structural components of the spine in patients with IS (surgical material). We have shown that IS develops on the basis of disturbance of proteoglycans (PG) synthesis and formation in vertebral growth plates. The found keratan sulphate-related fraction is likely a marker of genetic changes in PGs in IS. Long-term our studies demonstrated a major-gene effect in IS. The study has shown that aggrecan gene expression is significantly decreased in cultivated chondroblasts from patients with IS. The presence of keratan sulphate-related fraction and keratan sulphate increase are associated with lumnican increase.