|| The impact of body mass index (BMI) on postoperative survival in Japanese patients with pancreatic cancer is unclear. We examined the relationship between preoperative BMI and the prognosis of Japanese patients who underwent surgery for pancreatic cancer to determine whether BMI affects these patients’ prognosis. Of the patients who underwent pancreatectomy between January 2004 and August 2015 at our institution, 246 were pathologically diagnosed with pancreatic tubular adenocarcinoma; the cancer was located in the pancreatic head (n=161) and in the body and tail (n=85). We classified the patients by BMI: underweight (n=22), normal weight (n=190), and overweight/obese (n=34) groups. We retrospectively analyzed medical records for patient characteristics, lesion location, disease stage, postoperative complications, chemotherapy, and prognosis. Lesion location, disease stage, postoperative complications, and chemotherapy were not significantly different among the BMI groups. The median survival times were as follows (days): all patients, 686; underweight, 485; normal weight, 694; and overweight/obese, 839. In a multivariate analysis, after adjusting for competing risk factors, low BMI was associated with an increased risk of death (normal weight: HR 0.58, p=0.038; overweight/obese: HR 0.54, p=0.059). High BMI was not found to be a postoperative factor for poor prognosis in Japanese pancreatic cancer patients.