Objective To study the pathological changes and virus content of commonly used mice artificially infected with murine norovirus ( MNV). Methods Five strains of common experimental mice ( KM, BALB/ c, NIH, C57BL/ 6 and BALB/ c-nu) were used. Each strain was divided into a control group and an infection group. The infection group was administered MNV solution by gavage and the control group was given saline. Liver, spleen, lung, cecum, colon, and small intestine tissues were collected on days 7, 14, 21, 28, and 55 after infection. Two samples were taken from each tissue; one was for pathological diagnosis and the other was tested for viral nucleic acid content. Results No lesions were found in the cecum, colon, and small intestine. The total incidence of liver, spleen, and lung pathological changes was 8% (10 / 125), 5. 6% (7 / 125) and 4% (5 / 125), respectively. Pathological changes were found in the liver, spleen and lung of KM and BALB/ c mice, the liver and lung of C57BL/ 6 mice, and the liver and spleen of NIH and BALB / c-nu mice. Among them, KM mice were more likely to develop lung lesion. Pathological changes occurred earlier in KM and NIH mice than in C57BL/ 6 mice. MNV nucleic acid positive rates in the cecum and colon were 100% ( 125 / 125), and the positive rates in the small intestine, liver, spleen, lung, and blood were 71. 2% (89 / 125), 17. 6% (22 / 125), 39. 2% (49 / 125), 3. 2% (4 / 125), and 1. 6% (2 / 125), respectively. Comparison of virus contents showed the following order: cecum> colon> small intestine> spleen> lung> liver. BALB/ c-nu mice had significantly higher colon virus contents than the other strains (P < 0. 01), and there was no statistical difference among the remaining tissues of each strain. The cecum and colon virus contents in C57BL/ 6 mice peaked on day 14 after MNV infection (P< 0. 05), but there was no statistical difference in virus contents at other time points in the other strains. There was no correlation between tissue and organ pathological examination and viral nucleic acid test result . Conclusions MNV infection in mice can cause pathological changes in tissues of commonly used experimental mice. It is recommended that MNV-negative mice be selected for pathologically related animal experiments.