PURPOSE: To describe variations of the main and right portal veins as visualized by indirect portograms and to examine the surgical implications of these findings. MATERIALS AND METHODS: A retrospective review was conducted of 632 indirect portograms of 632 patients in whom third-order branches were visualized. All patientsalso underwent dynamic CT and AP and oblique hepatic angiography. RESULTS: Variations of the main portal veinwere found in 165 patients(26.1%) and involved an immediate trifurcation of the main portal vein in 102 patients(16.1%), early division of the right posterior portal vein in 53(8.4%), simultaneous division into fourbranches in three (0.5%), five branches in two (0.3%), a replaced P4 originating from the right portal vein in two(0.3%), and an accessory P6 originating from the main portal vein, a replaced P6 originating from the main portalvein, or a replaced left lateral portal vein originating from the right portal vein in one (0.2%), respectively.Of 468 patients who had a common right portal vein, absence of the right posterior portal vein was seen in 26 patients(5.6%) and an accessory subsegmental branch originating from the right portal vein in 17 patients(3.6%). CONCLUSIONS: Recognition of such variations of the portal vein assists in the localization and appreciation ofthe hepatic segmental anatomy, in preoperative evaluations for hepatic resections, and in radiologic interventional procedures through the portal vein.