The aim: To investigate the effectiveness of determining the activity of faecal calprotectin for detecting colonic lesions in patients with nonalcoholic fatty liver disease who have had a COVID-19 acute respiratory infection. Materials and methods: The study included 46 patients with non-alcoholic fatty liver disease NAFLD at the stage of outpatient observation after suffering a COVID-19 acute respiratory infection. Results: One of the main clinical signs indicating intestinal lesions among the COVID-19-infected patients with NAFLD at the time of admission to hospital was diarrhea (identified in 43.5% of cases during the patients’ examination), as well as bloating and pain in the colon (identified in 26.1% and 32.6% of cases during the patients’ examination, respectively). The analysis of the data obtained indicates a slight increase in the level of faecal calprotectin among NAFLD patients infected with COVID-19 during hospital treatment, and in this regard the indicators did not exceed the reference values. A more pronounced deviation from the norm was observed 2 months after hospital treatment, namely, its increase to 101.6 ± 2.5 μg / L. Conclusions: A frequent clinical manifestation of intestinal lesions among NAFLD patients infected with COVID-19 is defaecation disorder, which at the beginning of the disease is more often manifested through alternating diarrhea (up to 43.5%) and constipation (32.6% of the examined patients). NAFLD patients infected with the COVID-19 virus are diagnosed with an intensified activity of faecal calprotectin and α1-antitrypsin in the blood serum and faeces, as well as the clearance, and this indicates the presence of inflammatory changes in the colon, which requires conducting further research of these patients’ cases.