Activation of digestive zymogens by lysosomal enzymes has been suggested as a triggering event in acute pancreatitis (AP). Chloroquine (CQ), a weak base that accumulates in the lysosomes and increases their pH, can inhibit the activity of lysosomal enzymes. In the present study, we examined the effect of CQ on choline-deficient, ethionine-supplemented (CDE) diet-induced AP. CQ-diphosphate (15–50 mg • kg−1) or vehicle was given intraperitoneally at 0, 24, and 48 h to female CD1 mice that were fed with either normal diet or CDE diet. For mortality studies, animals were observed for 168 h. Serum and pancreas samples were collected from animals sacrificed 56 h after the start of the CDE diet. Treatment with CQ at 50 mg • kg−1significantly (p< 0.05) improved the survival of mice with CDE diet-induced AP. In the normal pancreas, CQ decreased the specific activity of lysosomal enzymes cathepsin B1, β-hexosaminidase, β-glucuronidase, and acid phosphatase. In the pancreas with AP, CQ did not modify the activity of cathepsin B1, whereas it increased the latency of all enzymes. In conclusion, our results confirm the beneficial effect of CQ on survival of mice with CDE diet-induced AP and suggest that this effect of CQ may be due to its stabilizing action on lysosomes.