Portal vein thrombosis is one of the main prehepatic causes of portal hypertension. The most frequent causes of thrombosis in this localization, apart from hepatic cirrhosis, are the following: acute inflammatory diseases and abdominal cancers, traumas, proliferative diseases of the hematopoietic system. In recent years attention was given to disorders in hemostasis, such as thrombophilia, in the course of which thrombosis development is particularly common. The authors present 10 patients after an incident of portal vein thrombosis, in which primary hepatic pathology was excluded and tests directed at thrombophilia were performed. In seven patients abnormalities in the examined parameters were found, and what is more, in two cases they had a complex character and involved more than one parameter. In five patients hyperhomocysteinemia was found. Among them, in two patients there was also a decreased protein S activity and in one of them there was also APC-resistance. In the next two patients there were abnormalities in one of the examined parameters - APC-resistance. Hyperhomocysteinemia was found in all patients with idiopathic thrombosis, and in one of them there were concurrent changes in protein S activity and APC-resistance. In patients with the history of portal vein thrombosis diagnostics of thrombophilia should be performed.