To develop a technique for performing laparoscopy in the mouse.Controlled animal study (Canadian Task Force classification II-1).University research laboratory.Twenty-eight CD-1 pregnant mice.Eight mice underwent anesthesia only and 20 had anesthesia plus laparoscopy at 5.5 and at 10.5 days' gestation (implantation occurs on day 4.5 and delivery on days 19-20).Four mice in the laparoscopy group died early in the series, three due to hemorrhage and one due to anesthetic overdose. Among survivors, there were no differences between operated and control groups in number of pups delivered at term (8.7 +/- 5.1 and 8.9 +/- 3.8, respectively), frequency of pregnancy failure (18.8% and 12.5%), and presence of intraabdominal adhesions on autopsy after delivery (12. 5% and 12.5%). Intraabdominal contents could be manipulated to visualize both uterine horns in their entirety. The number of gestations could be counted accurately as early as 1 day after implantation.Given the fact that laparoscopy is not accompanied by the immunosuppression characteristic of laparotomy, this technique could prove useful for investigations requiring intraabdominal manipulations in mice when preservation of immune function is critical. The technique can be performed safely and repeatedly after an initial learning period. (J Am Assoc Gynecol Laparosc 6(2):173-177, 1999)