Aim of the study: Portal vein thrombosis (PVT) is a well-known consequence of cirrhosis. Its pathophysiology is complex, with possible downstream hepatic decompensation. This study was conducted to describe the changes of protein C (PC), protein S (PS) and D-dimer blood levels associated with PVT formation in cirrhosis and the relation to the degree of liver dysfunction. Material and methods: This was a case-control study that included 50 cirrhotic patients who presented with acute de novo non-malignant PVT and 50 cirrhotic patients without PVT as a control group. The severity of liver disease was classified as per the Child-Turcotte-Pugh (CTP) score. Doppler ultrasonography identified acute portal vein occlusion, and dynamic contrast-enhanced computed tomography confirmed the extent and nature of PVT. Blood PC, PS and D-dimer levels were measured using enzyme-linked immunosorbent assay. Results: PC and PS levels were significantly lower, and the D-dimer level was significantly higher, in cirrhotic patients with PVT compared to the control group. PC and PS levels were significantly decreased in patients with higher CTP score of both groups. The D-dimer level did not vary significantly with the degree of liver dysfunction in patients of either group. PC, PS and D-dimer at the cut-off points of ≤ 77 IU/dl, ≤ 63 IU/dl, and > 300 ng/ml, respectively, significantly suggested PVT occurrence. Conclusions: Alteration of the anticoagulant proteins and D-dimer contributed to PVT formation in cirrhotic patients and could help stratify the degree of liver dysfunction. Blood level of these hemostatic proteins could be incorporated into a probability score for early diagnosis and treatment of PVT in cirrhosis.