Objectives: to increase informationvalue of computed tomography (CT) scan in assessing liver size Material and methods. The CT scan of the abdominal cavity of 108 patients from Moscow Radiological information system have been analysed. Measurement of three liver sizes, namely: width, height and thickness. Has been carried out 3D reconstruction of liver has been made on basis of its segmentation in the special module of the multimodal station Philips (IntelliSpase Portal), which permit to determine the organ volume with high accuracy. Results. It is established that in most cases (52%) judgment of liver volume is based on one kraniokaudal dimention of the right lobe. The number offalse positive results in determining the volume of the liver, according to the CT scan is 33.3% (specificity and predictability of the negative result is 60%), which reflects the hepatomegaly’s overdiagnosis. Using this data, it's been revealed that there are 2 sizes whose summation has a strong relation to the volume of the organ among all common linear size: craniocaudal and anteroposterior dimentions of the right lobe (r = 0,85). The most convenient in practice parameter for establishing the fact of a hepatomegaly is determined as the sum of given sizes and borderline value, that is 36 cm, is determined. The usage of this parameter reduces the number of false positive results to 5,6% and raises efficiency indicators of determinating of liver volume (specificity and predictability ofnegative result amount to 93,3%). Formulas for obtaining values of organ volume on the basis of two and three linear sizes of the right lobe liver sizes are developed. Conclusions. At present, there is a tendency of hyperdiagnosis of hepatomegaly, the cause of which is a complex and diverse form of the liver. The usage of the developed parameter that is the sum of the kraniokaudal and front-back the right lobe sizes increases accuracy for establishing the the fact of a hepatomegaly.