Objective To establish acute peritonitis induced by monosodium urate (MSU) of in mice and observe the significance of mitochondrial deoxyribonucleic acid (mtDNA) expression in the inflammatory processes.Methods The mouse models of acute peritonitis were made by intraperitoneal injection of MSU.Sixty-four male C57BL16 mice were randomly divided into the MSU group which were treated with 0.2 ml of 15 mg/ml MSU solution by i.p.injection and the control group which were treated with 0.2 ml of PBS.Respectively four mice from MSU group and four mice from control group were killed 2 hours, 4 hours, 6 hours, 8 hours 12 hour, 16 hours, 20 hours and 24 hours later and whole blood, peritoneal lavage and peritoneum were collected respectively.Four the mice from the MSU group and four mice from the control group were killed and whole blood, peritoneal lavage and peritoneum were collected.Immunoflourescence study of peritoneum tissues was performed.The levels of interleukin (IL)-1β, IL-18 in plasma and peritoneal lavage were examined by enzyme linked immunosorbent assay (ELISA).DNA was extracted from blood and peritoneal lavage, and mtDNA level was detected by using real-time polymerase chain reaction (PCR).The data was analyszied by multivariate analysis of variance.Results As compared with those killed at other time points from the MSU groups and the control group, the levels of IL-1β [(27.0±2.0) pg/ml vs (26.8±2.1) pg/ml], IL-18 [(673±454) pg/ml vs(752±495) pg/ml] in plasma and peritoneal lavage were increased progressively in those which were killed after i.p.injection of 2 hours and 4 hours from in the MSU group (F=22.778, P＜0.05;F=6.660, P＜0.05).The mtDNA in plasma and peritoneal lavage of the mice began to be expressed 4 hours after i.p.injection 4 hours from in the MSU group.The peak level was detected in those i.p.injected MSU 6 hours later [(9.85±4.59)×106 copies, (7.81±3.43)×106 copies].Then 8 hours later the mtDNA began to slowly decreased.At these three time points, the mtDNA were all increased progressively than those at the other time points of the MSN group or at all time points of the control group (F=6.719, P＜0.05;F=11.181, P＜0.05).By immunoflourescence study, there were neutrophil extracellular traps (NETs) were formed 12 hours later in the MSU group and aggregated NETs were found 24 hours later.Conclusion In the inflammatory processes of acute peritonitis induced by MSU of in mice, with the expression of mtDNA increasing, the inflammation is relieved, and aggregated NETs are formed in the end.Expression of mtDNA may be one for the protective factors of the inflammation induced by MSU.