Background/Objectives: The aim of this study is to explore the relationship between length of hospital stay and mean corpuscular hemoglobin (MCH) in acute pancreatitis (AP) patients.Methods: The study included 273 AP patients without coronary heart disease, diabetes, hypertension, tumor, psychosis and anemia. The clinical data was collected from electronic medical records.Results: We separated all data into three groups according to length of hospital stay. We observed that gender (P=0.017) and severity classification (P=0.000) were significantly correlated with length of hospital stay among three groups. Notably, MCH level was significant increased among three groups (30.02±1.91, 30.21±1.81, 30.92±2.47 pg, P=0.009). Thus, we separated all data into two groups according to MCH level, and observed significant increases of length of hospital stay between two groups (11.95±7.03, 13.96±8.18 days, P=0.030). A positive correlation between length of hospital stay and MCH was observed in these individuals (r=0.172, P=0.004). Multiple linear regression analysis showed that MCH was independent correlated with length of hospital stay, no matter whether severity classification of AP was included (beta=0.248, P=0.000; beta=0.212, P=0.000).Conclusions: We concluded that length of hospital stay is correlated with MCH level in AP patients, and the MCH level may predict length of hospital stay independent of severity classification in this disease. Our results may provide a potential evaluation basis for the management of patients with AP.