Background and study aim : Portal hypertension leads to formation of portosystemic collateral veins as oesophageal varices in patients with liver cirrhosis. Several studies have shown that blood ammonia is a vauable non invasive marker of oesophageal varices. This study is designed to evaluate the possible relation between blood ammonia level and oesophageal varices in patients with liver cirrhosis. . Patients and Methods: This study was conducted on three groups of patients and control subjects. Group I included 20 cirrhotic patients without evidence of oesophageal varices. Group II included 40 cirrhotic patients with evidence of varices. Group III included 20 healthy control subjects. Serum level of ammonia were done for all patients and control subjects. Results: There was a highly significant increase in the mean values of blood ammonia in cirrhotic patients with varices in comparison to other patients without varices, with highly significant positive correlation between serum ammonia and size of varices. There was a significant increase in the mean values of blood ammonia in cirrhotic patients with grade III and IV varices [large varices) in comparison to cirrhotic patients with grade I and II varices. Conclusion:Blood ammonia level is a valuable, simple non invasive marker for prediction of oesophageal varices.