Purpose To assess the risk of developing thoracogenic scoliosis (THS) in paediatric patients, depending on the side of lateral thoracotomy (LT) and of spine deviation in the coronal plane by means of logistic regression and scoliosis-free survival analyses. Methods A total of 307 consecutive patients undergoing LT were retrospectively reviewed; 32 patients met the inclusion criteria: 1) underwent LT and developed THS; 2) age < 15 years at LT; 3) clinical and radiographic follow-up ≥ 5 years. Patients were divided into ipsilateral group (convexity ipsilateral to LT) and contralateral group (convexity contralateral to LT). Results The mean follow-up was 10 ± 4.7 in the ipsilateral group (n = 13) and 12 ± 4.8 years in the contralateral group (n = 19). The contralateral group underwent LT at a younger age (4.4 vs 6.4 years, p = 0.55), developed more severe coronal deformity (27.8° vs 18.9°, p = 0.15), had higher rate of THS > 20° (47.5% vs 38.4%; p = 0.34) and > 45° (21.1% vs 0%; p = 0.99). The mean time from LT to THS diagnosis was 4.2 ± 2.9 in ipsilateral group and 5.5 ± 4.2 years in contralateral group. Left-side LT (p = 0.03) and age > 5 years (p = 0.01) showed a lower risk of THS diagnosis. The group variable had a statistically significant effect on the risk of developing THS > 45° (p = 0.03). Conclusion In this series, children that developed THS with a convexity contralateral to the side of LT had more severe and progressive coronal spine deformity. Level of evidence: III