['Pancreatectomy, including pancreatoduodenectomy and distal pancreatectomy, often causes postoperative pancreatic exocrine insufficiency (PEI). Our aim was to clarify a relationship between remnant pancreatic volume and postoperative PEI.', 'A total of 227 patients who underwent pancreatoduodenectomy or distal pancreatectomy were enrolled in this study. All patients underwent a (13)C-labeled mixed triglyceride breath test to assess pancreatic exocrine function and abdominal dynamic computed tomography for assessing remnant pancreatic volume after pancreatectomy at a median of 7 months postoperatively. The percent (13)CO2 cumulative dose at 7 hours (% dose (13)C cum 7 h) < 5% on the (13)C-labeled mixed triglyceride breath test was considered diagnostic of postoperative PEI. Relationships between postoperative PEI and clinicopathologic factors including remnant pancreatic volume were analyzed.', 'Pancreatoduodenectomy and distal pancreatectomy were performed in 174 (76.7%) and 53 (23.3%) patients, respectively. Of the 227 patients, 128 (56.3%) developed postoperative PEI. Postoperative % dose (13)C cum 7 h was strongly correlated with remnant pancreatic volume (r = .509, P < .001). The cut-off value of remnant pancreatic volume for predicting postoperative PEI was 24.1 mL by receiver operating characteristic curve analysis. Multivariate analysis revealed that remnant pancreatic volume < 24.1 mL was the only independent predictive factor for the development of postoperative PEI in patients who underwent pancreatectomy (P < .001, hazard ratio; 5.94, 95% confidence interval; 2.96-12.3).'] Does remnant pancreatic parenchymal volume predict postoperative pancreatic exocrine insufficiency after pancreatectomy?