Abstract : <p>This study determined cardiac sizes, with the aid of chest radiographs, using the mean values of the CTR among adult Ijaws in Nigeria. Chest radiographs of 200 adult Ijaws were obtained and placed on a radiological illuminator box to reflect proper views of the radiographs, as cardiac and thoracic diameter values were collected. Data were analysed using SPSS for total number determination, mean, range, standard deviation and t-test value. The results recorded as follows; mean cardiac diameter for males is 13.44&plusmn;1.10cm; that for female is 12.52&plusmn;1.20cm and 12.98&plusmn;1.19cm was recorded for both gender. For mean thoracic diameter, male value is 29.76 &plusmn; 1.85cm, that of female is 26.77&plusmn;1.84cm and 28.26&plusmn;2.37cm was recorded for both gender. Also the mean CTR (cardio-thoracic ratio) value was also recorded; the value for male is 45.22&plusmn;3.19, that for female is 46.88&plusmn;3.87 and 46.05&plusmn;3.63 was recorded for both gender. Statistical analysis using student t-test showed that male adult Ijaws had higher value (p&lt;0.05) in almost all the parameters except in CTR value, whereas females have higher CTR value (p&lt;0.05). Findings of the index study (46.05 CTR values) provides a reference point for future studies on other Nigerian ethnic groups, which will in turn enhance better clinical interpretations necessary for diagnosing cardiovascular disorders.</p>