Background: The chest radiograph provides excellent contrast between the air-filled, cardiac, and aortic outlines. Deviations from normal measurements suggest pathology. This study was aimed at measuring the selected normal chest morphometry of Nigerians residing in Port Harcourt to establish a baseline for people in a normal condition. Materials and Methods: This was a retrospective descriptive study carried out in the Radiology Department of the University of Port Harcourt Teaching Hospital, Rivers State. The study duration was 8 months (January–September, 2021), which involved four hundred and forty-eight (216 males and 232 females) normal chest radiographs of adult Rivers aged between 18 and above. The radiographs were found to be normal by a qualified radiologist in the department. Random sampling was used to determine the sample size for the study. Results and Discussions: For adult males aged 18 and up, the mean values of all measured parameters were: TAD (cm): 4.15 ±21.54; TCD (cm): 10.88 ±1.55; WITD (cm): 26.06 ±3.25; and mean age (yrs): 44.15 ±21.54. TAD (cm) was 5.11±0.69 in females, TCD (cm) was 10.8±21.50, WITD (cm) was 26.05±2.98 and the mean age (yrs) was 40.93±20.22. In the two variables (TCD and WITD), the males had slightly higher values than the females, although not significantly higher, while the females had a higher TAD, also not significantly higher. Conclusions: The correlation between the transverse aortic diameter and the transverse cardiac diameter for female subjects; the correlation between the transverse aortic diameter and the transverse cardiac diameter for male subjects; and the correlation between the transverse cardiac diameter and the widest internal thoracic diameter were all positively correlated (r = 0.611, r = 0.566, r = 0.822, P 0.05).