Abstract: Pancreatic ductal adenocarcinoma (PDAC) continues to have a dismal prognosis, with a 5-year survival rate of < 5%. Recent progress in chemotherapy has provided an improved median survival time (MST) in patients with unresec-table PDAC. The treatment of unresectable PDAC is still a clinical challenge which may require a multidisciplinary approach. Recent chemotherapy provided the good response rates and the increased rate of conversion surgery in locally advanced PDAC as well as metastatic one. Several articles revealed that high resectability (20%-61% in patients with URLA-PDAC), high margin-negative resection rate (27%-89%), and high negative lymph node rate (29%-86%) were found in patients with initially UR-PDAC who underwent conversion surgery. Most of article revealed acceptable mortality and morbidity in patients who underwent conversion surgery. The MST ranged from 24 to 56 months in patients who underwent conversion surgery, which was significantly higher than those in patients who did not undergo surgical resection. An appropriate regimen of chemotherapy and measure of tumor remission, surgical indication, optimal time of conversion surgery, and extent of surgical resection are still under investigation. Thus, conversion surgery can be the important key to open the door for improving long-term survival in patients with unresectable PDAC. Sustainable efforts are warranted to conduct a decently designed clinical trial to confirm efficacy of conversion surgery in the subset of patients with initially UR-PDAC.