Abstract: OBJECTIVE To explore the correlation between mRNA level of matrix Gla protein (MGP) in peripheral blood and severity of cytomegalovirus (CMV) infection in patients with ulcerative colitis. METHODS Total of 83 patients with UC admitted to Quzhou People's Hospital were between Mar 2020 and Mar 2023 were recruited, including 29 cases with CMV infection as the CMV group and 54 cases without CMV infection as the non-CMV group. Another 50 healthy volunteers under physical examination were enrolled as the control group. The laboratory indexes were tested routinely, and mRNA expression of MGP in peripheral blood was detected by real-time fluorescence quantitative reverse transcription-polymerase chain reaction (RT-PCR) assay. The differences in the indexes among groups were compared. RESULTS The course of disease in the CMV group was longer than that in the non-CMV group, and the proportion of severe disease, use rates of glucocorticoids and immunosuppressants and glucocorticoid resistance rate were higher than those in the non-CMV group (P＜0.05). White blood cell count (WBC), erythrocyte sedimentation rate (ESR), and levels of high-sensitivity C-reactive protein (hs-CRP) and MGP mRNA in the CMV group were higher than those in the control group and non-CMV group (P＜0.05), and the mRNA levels of WBC, ESR, hs-CRP and MGP in the non-CMV group were higher than those in the control group (P＜0.05). The levels of WBC, ESR, hs-CRP and MGP mRNA in severe patients were higher than those in moderate patients of the CMV group (P＜0.05). MGP mRNA level in peripheral blood of UC patients complicated with CMV infection was positively correlated with WBC, ESR, hs-CRP and severity of disease (P＜0.05). CONCLUSION In the process of MCV infection in patients with UC, the expression of peripheral blood MGP mRNA increases, which is related to disease activity and can be used as a reference indicator for evaluating disease severity.