Background: The optimal timing of surgery is still controversial when preoperative gallbladder drainage (PGD) has been performed for AC. Method: Between 2010 and 2015, 77 AC patients, who consecutively underwent surgery, were divided into two groups. One was the group on which PGD were performed (n=39), and the other was patients that underwent emergency operations (EO) without PGD (n=38). The PGD group was further divided into two groups: one with the period from drainage to surgery of ≦14 days (PGD-E:n=17) and in the other the period was >14 days (PGD-D:n=22). The surgical outcomes were compared between these groups. Results: The blood loss of the PGD group was significantly less (159.7/354.3 ml : p=0.028) compared to the EO group. In the PGD-E group the total hospital stay was significantly shorter than that of the PGD-D group (29/40.8 days : p=0.041). There were no significant differences between PGD and EO when limited to patients who underwent laparoscopic cholecystectomy (LC). Conclusion: Surgery within 14 days after PGD might be as safe as surgery over 14 days after PGD. With regard to shortening the total hospital stay, surgery within 14 days after PGD might be recommendable.