A short description is given of the techniques for percutaneous transhepatic (PTP) and transumbilical (TUP) portal Venous catheterization and their use for direct selective catheterization of the portal vein and its tributaries. PTP was successful in 181 of 184 attempts (98 per cent) and TUP in 283 of 301 attempts (96 per cent). The complications are discussed in details. Among the clinical implications of the methods is the diagnosis of hormone producing tumours.