Aim: The primary purpose of this study is to evaluate if, on an unenhanced CT, the attenuation of blood in the aorta correlates with haemoglobin levels and to evaluate the specificity of aortic ring sign and the hyperdense interventricular septum and myocardium in detection of anaemia. Materials-methods: We performed a retrospective study on 70 patients who had undergone unenhanced CT of the thorax at the K.V.G Medical College Hospital, Sullia, between august 2018 and January 2019. Results: Anaemia is defined as less than 14g/I for a male and less than 12g/I for a female, then, in our study group, no male with an aortic attenuation value greater than 50HU and no female with an aortic attenuation greater than 45HU was found to be anemic. A good correlation was observed between the aortic CT attenuation values and the haemoglobin levels in the study group. Conclusion: The results demonstrate the significant correlation between the haemoglobin assay and the aortic attenuation value. This provides a feasible means to detect anaemia in unenhanced CT examination.We conclude that this information may provide a valuable adjunct in the interpretation of such examinations.Currently, the observed correlation is not strong enough to offer a definite diagnosis of anaemia; however, a larger sample size is likely to strengthen the predictive value of an HU cut-off value for anaemia.