Background Progressive weight loss has been determined to be an important prognostic factor in various malignancies. In particular, in pancreatic cancer many patients develop a dramatic cachexia syndrome during the progression of their disease. Therefore, the aim of the study was to examine the influence of cachexia on perioperative morbidity and mortality and its impact on the outcome of patients with resectable pancreatic cancer. Material and methods: From June 2004 to November 2005, 220 patients with ductal adenocarcinoma of the pancreas were admitted to our department for surgical therapy. We defined cachexia as an unintended loss of body weight of more than 10% of the original weight within 6 months. The data of all patients were collected in a prospective database. Each patient gave his informed consent for data collection and collection of blood samples for research. Results: Of the included 220 patients with histologically proven ductal adenocarcinoma of the pancreas, 38.5% presented with cachexia (median weight loss 12 kg), 61.5% had no or less than 10% weight loss (median weight loss 0 kg). There was no significant difference between the two groups regarding age (P=.606), gender (P=.413), ASA-classification (P=.455), tumor size (P=.458), lymph node metastasis (P=.87), and grading (P=.308). Tumor stage at time of operation in cachectic and non-cachectic patients was UICC II in 50.0% versus 66.7% and UICC IV (metastatic disease) in 46.1% versus 29.8%, respectively (P=.03). A significant difference regarding resection rate was determined, with 50% in the cachectic versus 72.6% in the non-cachectic group (P=.001). The perioperative morbidity rate revealed no significant differences in both groups (P=.653). However, there was a significant difference in perioperative mortality, with a worse rate for cachectic patients (P=.034). In palliative, non-resected patients, the overall survival was shorter in the cachectic group than in the non-cachectic group with a median survival of 91 days versus 181 days, respectively; in resected patients, both groups showed statistically non-significant differences. Conclusion: In patients with pancreatic cancer, cachexia is a considerable prognostic factor which is still underestimated. Cachexia significantly worsens the prognosis of patients with pancreatic cancer regarding resection rate, perioperative mortality and survival. Surprisingly, occurrence of cachexia is independent of tumor size or lymph node status, but significantly correlated to aggressivness of the tumor and the potential to metastasize.