BACKGROUND Laparoscopic splenectomy has become an important therapeutic option in the management of diverse hematologic disorders. However, the incidence of important complications, such as portal vein thrombosis, remains poorly understood. We set out to study the incidence of this complication over a 14-month period. METHODS All adult patients who underwent laparoscopic splenectomy between July 2001 and April 2002 at McMaster University Medical Centre in Hamilton, Ont., were approached postoperatively and offered duplex ultrasonography of the portal vein to look for thrombosis. RESULTS During the study period 17 patients underwent laparoscopic splenectomy. Two patients declined to participate, and in 1 patient the ultrasonography was technically inadequate. Of the 14 remaining patients, 2 (14%) were found to have portal vein thrombosis. In 1 other patient, the investigation was suggestive, but not conclusive, of a clot in the portal system. CONCLUSIONS Portal vein thrombosis in this series was a relatively common complication of laparoscopic splenectomy. Further research is needed to confirm our findings.