The aim of this study was to determine the influence of lateral thoracotomy on the development of scoliosis in subjects undergoing repair of coarctation of the aorta (CoA) and patent ductus arteriosus (PDA). A group of 133 patients with CoA and PDA was evaluated. Forty-five patients with CoA and 38 with PDA underwent surgery using standard posterolateral thoracotomy (operative group), whereas 12 patients with CoA and 31 with PDA were treated using balloon dilatation and stent or coil implantation (nonoperative group). A spinal examination, together with the evaluation of chest and spinal roentgenograms, was conducted. Among the operated patients, 62% of those with CoA and 55% of those with PDA had clinical scoliosis. In the nonoperated patients, scoliosis was present in only 25% of those with CoA and 16% of those with PDA. Scoliosis ranged between 10° and 42°. In 89% of the operated patients with CoA and 76% of those with PDA the curve was thoracic; in 46% of the CoA group and 57% of the PDA group the curve was left-sided. All curves were right-sided in nonoperated subjects. Scoliosis in the operated group was higher in male than in female subjects (63% vs. 60% in CoA and 86% vs. 37% in PDA). The prevalence of scoliosis after standard posterolateral thoracotomy was significantly higher than after nonsurgical treatment methods in the CoA and PDA groups as well as in the general population. The rate of single thoracic and the rate of left-sided thoracic curves in patients after thoracotomy is higher than in nonoperated patients or in those with idiopathic scoliosis. The rate of scoliosis after thoracotomy is higher in male than female patients, especially after thoracotomy for PDA.