Objective: to study the features of CT and MRI diagnostics of desmoid fibroids (DF) in familial colon adenomatosis (SATC). Patients and methods: the study included 35 patients with desmoid fibroids (DF) in familial colon adenomatosis (SATC). All patients were examined using computed tomography (CT) and magnetic resonance imaging (MRI) with intravenous contrast. Localization, size, growth pattern, prevalence of DF, features of contrast and intensity of the MR signal on T2-VI and post-contrast T1-VI were evaluated. Twenty-five (71.4%) patients were observed in dynamics, including during systemic therapy. Results: in 21 (60.0 %) patients, a lesion of only one anatomical area was detected, and in 14 (40.0%) cases, a combined lesion of different anatomical zones was noted. In the majority of observations (33/35, 94.4 %) desmoid fibroids were detected in the mesentery and mesentery root of the small intestine, including with a combined lesion. The majority of patients (24/35, 68.6%) were diagnosed with a diffuse nodular form of growth; 13 (37.1%) had a nodular form and 6 (17.1%) had a diffuse form. Twenty-five patients (25/35, 71.4%) were repeatedly re-examined using CT (13/35, 37.1%) and MRI (12/35, 34.3%), in particular during systemic therapy. Conclusion: CT and MRI are the basic methods for detecting DF in SATC, allowing to determine the nature of tumor growth, to assess the prevalence of the tumor process and the degree of involvement of adjacent organs and structures. In dynamic observation and evaluation of the response of a desmoid tumor to systemic therapy, MRI has greater diagnostic capabilities compared to CT, since it takes into account not only the size of the desmoid, but also the intensity of the MR signal on T2-VI and the nature of the accumulation of contrast agent on post-contrast T1-VI with fat suppression.