BACKGROUND This study aimed to investigate the effects of maresin-1 (MaR1) in a mouse model of caerulein-induced acute pancreatitis (AP). MATERIAL AND METHODS Fifty C57BL/6 mice with caerulein-induced AP were divided into the untreated control group (N=10), the untreated AP model group (N=10), the MaR1-treated (low-dose, 0.1 μg) AP model group (N=10), the MaR1-treated (middle-dose, 0.5 μg) AP model group (N=10), and the MaR1-treated (high-dose, 1 μg) AP model group (N=10). Enzyme-linked immunoassay (ELISA) measured serum levels of amylase, lipase, tumor necrosis factor-alpha (TNF-alpha), interleukin-1ß (IL-1ß), and IL-6 and mRNA was measured by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Malondialdehyde (MDA), protein carbonyls, superoxide dismutase (SOD), and the ratio of reduced glutathione/oxidized glutathione (GSH/GSSG) were measured. Histology of the pancreas included measurement of acinar cell apoptosis using the terminal-deoxynucleotidyl transferase-mediated nick end-labeling (TUNEL) assay. Western blot measured Toll-like receptor 4 (TLR4), MyD88, and phospho-NF-kappaB p65, and apoptosis-associated proteins Bcl-2, Bax, cleaved caspase-3, and cleaved caspase-9. RESULTS Following treatment with MaR1, serum levels of amylase, lipase, TNF-alpha, IL-1ß, and IL-6 decreased, MDA and protein carbonyl levels decreased, SOD and the GSH/GSSG ratio increased in a dose-dependent manner. In the MaR1-treated AP mice, inflammation of the pancreas and the expression of inflammatory cytokines, pancreatic acinar cell apoptosis, Bcl-2 expression, and expression of TLR4, MyD88, and p-NF-kappaB p65 were reduced, but Bax, cleaved caspase-3, and cleaved caspase-9 expression increased. CONCLUSIONS In a mouse model of caerulein-induced AP, treatment with MaR1 reduced oxidative stress and inflammation and reduced apoptosis.