The computed tomography (CT) number is closely related to hematocrit level according to many of the previous reports. We measured the CT number in various organs, such as the frontal white matter, basal ganglia, occipital white matter, cerebrospinal fluid, liver, abdominal aorta, spleen, kidney, and psoas muscle. We correlated the CT numbers of the organs with hematocrit levels which were graded into 10% increments (20.0-29.9%, 30.9%, 40.0-49.9%). Thus the change of CT numbers in various organs according to the hematocrit level was analyzed. The increased CT numbers according to the 10% increment of hematocrit in the frontal white matter. basal ganglia, occipital white matter, liver, abdominal aorta, spleen cerebrospinal fluid and kidney were not influenced by hematocrit level the CT numbers in most of the there organs postitively correlated with hematocrit level, Therefore, it was concluded that in the differential diagnosis using CT numbers, the hematocrit level of patient must be taken into consideration.