Introduction: Recent research has shown that Brugada syndrome (BrS) is associated with interstitial fibrosis in the right ventricular outflow tract (RVOT) epicardium, thus suggesting that BrS does not just involve cardiac channelopathy but also includes cardiomyopathy. On the other hand, Brugada pattern ECGs are often observed in patients with pectus excavatum. The purpose of this study was to investigate whether thoracic deformity, along with mechanical compression of RVOT, were associated with BrS. Methods and Results: We recruited 17 male patients with symptomatic BrS, 32 male patients with asymptomatic BrS, and 30 age-matched male controls. Using computed tomography (CT) scans, we measured the maximal internal transverse diameter of the thorax (T) and the shortest anteroposterior depth from the internal aspect of the sternum to the anterior cortex of the vertebral body (D) at the level of the RVOT. We then evaluated the fragmented QRS (f-QRS) in the right precordial leads. D was significantly shorter, while T divided by D (T/D) was significantly greater, in patients with symptomatic and asymptomatic BrS than in the controls. Six patients with pectus excavatum (T/D≥3.25) were included in the BrS population. The f-QRSs was more frequently observed in symptomatic and asymptomatic BrS patients than in controls. The positive spikes within the QRS complex were more prevalent in patients with a greater T/D. Conclusion: Our results suggested that a narrow anteroposterior thoracic space could be associated with BrS via mechanical compression of the RVOT.