Abstract： Objective To investigate the feasibility,safety and effect of gasless laparoscopic surgery used in patients at the second trimester.Methods From Aug.2006 to Aug.2008,the data of 10 cases at gestational 15 - 24 weeks complicated by ovary benign tumors ( the diameters more than 5 cm) undergoing gasless laparoscopic surgery were studied retrospectively.Operation time,bleeding loss,period of hospitalization,the status of fetus and newborn babies,and peri-operative or postoperative complications were observed.Results All 10 cases were treated by gasless laparoscopic surgery,including 4 cases with mature teratoma,5 cases with epithelial tumors and 1 case with ovarian endometrioma.The mean time of surgery was (30 ± 5) minutes,the mean bleeding in the surgery was (30 ± 8) ml,the mean period of in hospitalization was ( 6 ± 2 ) days.The blood gas ( pH:7.42 ± 0.11,7.41 ± 0.18,7.42 ± 0.12 ),blood pressure [ mean arterial pressure (MAP):(90.4 ± 3.1 ),(90.6 ± 0.7 ),( 89.7 ± 0.8) mm Hg( 1 mm Hg =0.133 kPa) ] and heart rates [ ( 84.0 ± 1.6),( 84.3 ± 1.7 ),( 82.7 ± 1.1 ) bpm ] in all cases at pre,peri and postoperative time did not show statistical difference ( P all ＞ 0.05 ).The fetal hearts were all in the normal range preoperative,intraoperative and postoperative time (P ＞ 0.05 ).No perioperative and postoperative complications were observed.All the cases underwent term delivery.Fetal weight and Apgar score did not show abnormality.Conclusion Gasless laparoscopic surgery at the second trimester is feasible and safe to mother and fetus.