Hyponatremia is common in advanced liver cirrhosis. Recently it has attracted an interest as a possible prognostic factor for liver cirrhosis complications. This study was conducted to assess the prevalence of hyponatremia in complicated cirrhotic patients admitted to medical ICU and to identify its relationship to development and severity of these complications. 200 patients with liver cirrhosis were included in this study. According to serum sodium, they were classified into three groups: group 1 with serum sodium ≤130 meq/L (severe hyponatremia), group 2 with serum sodium from 131 to 135 meq/L (mild hyponatremia) and group 3 with serum sodium ≥136 meq/L (normo-natremia). Demographic, clinical, and laboratory variables were prospectively recorded for analysis. In our studyThe prevalence of total hyponatremia was 131/200 patients (65.5%) and those with severe hyponatremia were 91/200 (45.5%) .There was a statistically significant increase in frequency of occurance (p>0.01) and relative risk each of ascites (1.3fold),intractable ascites (9.5fold), spontaneous bacterial peritonitis (2.6fold), hepatic hydrothorax (1.5fold) and hepatic encephalopathy (2.8fold), in hyponatremic groups compared to normonatremic one while there was no significant difference regarding hepatorenal syndrome, esophageal varices and variceal bleeding between different groups. Also there was a statistically significant negative correlation betwee serum sodium level and the two scoring systems: Child-Pugh score (r =-0.690, p<0.001) and Model for Endstage Liver Disease (MELD) score(r =-0.586, p<0.001). We can conclude that In critically ill patients with liver cirrhosis, the prevalence of total hyponatremia(Na ≤ 135 meq/L) was 65.5% while those with severe hyponatremia (Na ≤130) was 45.5%. Low serum sodium level was associated with high complications of liver cirrhosis. The relative risk of occurance, frequencies and severity of ascitis, intractable ascitis, hepatic hydrothorax, hepatic encephalopathy and spontineous bacterial peritonitis were increased in cirrhotic patients especially those with serum sodium levels ≤ 130 meq/L.So the Management of hyponatremia may decrease the incidence and severity of the liver cirrhosis complications with better quality of their life. Thus more interest should be tried towards the use of vasopressin receptor antagonists as a line of treatment of complicated cirrhotic patients with hyponatremia without salt overload