RÉSUMÉ
Background: There is paucity of data on cardiac sizes and other related parameters among Africans. This study aims to establish normal values of aortic, cardiac and thoracic diameters and the cardiothoracic ratio in a normal Nigerian population. Methods: The cardiothoracic ratio of 200 males and 200 females aged between 5 and 95 years were calculated from the cardiac and thoracic diameters in posteroanterior chest radiographs in a cross-sectional study at two imaging and radiodiagnostic centres. The mean and standard deviation of aortic, cardiac, thoracic diameters and cardiothoracic ratio were established. Results: The mean values for cardiac diameter for males and females were 13.8±1.89 and 13.2±1.28cm respectively. The mean values of cardiothoracic ratio for both male and female were 46% and 48% respectively. Conclusion: The cardiothoracic ratio increased with age in both sexes. These values were larger than those reported for the Caucasians.