The aim of this study was to present the authors’ experience with identification and classification of thyroid ophtalmopathy activity. A total of 46 orbits from 23 patients with thyroid ophthalmopathy symptoms were evaluated on computed tomography images in terms of diameters and density of extraocular muscles, muscular index, proptosis, width of the optic nerve, width of superior ophthalmic vein and lacrimal gland position. Radiological symptoms of proptosis were present in 78.3% patients, while 80% cases of diagnosed proptosis were bilateral. The most frequently affected eye muscle was the inferior (61%) and medial (54%) rectus prior to superior (39%), lateral rectus (37%) and superior oblique (26%). The highest correlation between muscle enlargement and proptosis was noted in the case of inferior rectus (77%) and medial rectus (70%). 78% of muscle enlargement was bilateral. Anterior displacement of the lacrimal gland was observed in 58% of cases. Width of the superior ophthalmic vein and the optic nerve (sheath complex) did not differ signifi cantly from normal population ranges. All muscles measured in the study had a lower density when compared to reference data; the density of the thickened muscles was lower than the density of muscles with an unmodified diameter.