The aim of this study is to describe the semiology for the assessment of breast asymmetry in the presence of scoliosis. Twenty-four women with right idiopathic scoliosis treated with bracing alone (23 out of 24) or with bracing and spine surgery (1 out of 24) were evaluated by physical and morphological examinations and three-dimensional (3D) surface scan. Physical examination revealed a smaller right breast in 20 women. A left costal protrusion was observed in 18 patients. Anthropomorphic analysis revealed that the right breast was higher in 19 cases, and smaller in 18 cases. The calculations from 3D scan showed the right breast to be smaller in 19 women. A strong correlation is found between clinical parameters, anthropomorphic measurements and 3D scan analysis, suggesting that a meticulous clinical examination is sufficient to evaluate breast asymmetry in patients with idiopathic scoliosis. A patient who is properly diagnosed and informed of her skeletal deformity and breast asymmetry is more likely to have realistic expectations from breast surgery.