Laparoendoscopic single-site (LESS) technique has gained popularity in several fields of surgery. Our patient had multiple gallstones and a left ovarian mature cystic teratoma 12 cm in diameter. She underwent concomitant laparoscopic cholecystectomy and adnectomy using LESS technique. Using a transient gasless technique resulted in the extraction of a giant ovarian tumor through the umbilical incision with no leakage into the abdominal cavity. Concomitant LESS surgery is feasible and has many benefits both for patients and doctors – cosmetics, possibly less pain, avoidance of multiple surgeries and cost-effectiveness. LESS technique is also useful for extracting a giant tumor with the transient gasless technique. This novel method might be applied to the removal of a tumor suspicious for malignancy.