The objective of this study is to describe the electrocardiographic signs associated with certain chest deformities. This is a prospective, case-control study comparing 20 black subjects with chest deformity (11 cases of flat back syndrome, 5 cases of pigeon chest, 4 cases of funnel chest) with 20 age- and sex-matched healthy controls. Cardiac duplex ultrasound was performed for each individual to exclude associated heart disease. Atypical electrocardiographic signs were observed in 15 subjects with chest deformity versus only 3 in the control group. The anomalies observed consisted of signs of atrial or ventricular hypetrophy, right branch block, abnormalities of repolarization on the T wave or ST segment. Chest deformities are therefore associated with several electrical signs simulating most cardiac diseases. A good knowledge of these modifications should help to avoid the numerous diagnostic traps associated with these signs.