Bulk densitywas determined indirectly in peat samples by X-ray computed tomography (X-ray CT) and compared with density values obtained by standard laboratory methods. Five Histosols were collected in the same cut-over peatland, representing various degrees of disturbance related to the process of peat extraction. Soil cores were fully imaged by X-ray CT with a voxel size of about 0.25 mm. Each one of these five attenuation profiles was analysed and compared with direct density measurements. A linear relationship, to convert attenuation values into density values, is proposed to determine the variation in bulk density with a spatial resolution clearly greater than standard laboratory determinations. It is also shown that X-ray-based density values can be effectively used to characterize the structure of peat soils and the possible consequences of disturbances after drainage and peat mining. Under the accepted limitations of the method, X-ray CT opens up new opportunities to determine the structural quality of peat and to monitor its modifications with time. This indirect diagnostic could be particularly useful to study peatlands’ hydraulic systems or evaluate the effectiveness of restoration measures.