Background/Aims: We examined the correlation between hyperammonemia and gastric Helicobacter pylori (H. pylori) infection in patients with liver cirrhosis. Methods: We studied 31 patients with liver cirrhosis and 34 normal controls. However, the cirrhotic group did not include patients who had a bleeding tendency or hepatic encephalopathy. We performed gastroscopy, obtained gastric juice (3-4 mL) and antral biopsy specimens, and examined the ammonia levels of blood and gastric juice in each group. Results: In the cirrhotic group, there was no difference in blood ammonia levels between the H. pylori- positive (HP+) and negative (HP-) groups. However, the ammonia levels of gastric juice in the HP+ group showed a tendency to be higher than those in the HP- group (p=0.0773). Child-Pugh scores in the HP+ group were significantly lower than those in the HPQ group (p= 0.0309). By multiple regression analysis, factors affecting the ammonia levels of blood were determined. They were age (coefficient 1.2462, p=0.0256) in the control group (r2=0.2821), and ammonia levels of gastric juice (coefficient 0.007417, p=0.0322) in the cirrhotic group (r2=0.3127). On the other hand, Child- Pugh scores (coefficient 12.508122, p=0.0883) indicated a slight correlation with the blood ammonia levels in the cirrhotic group. Conclusions: It seems that gastric H. pylori infection is associated with hyperammonia in patients with liver cirrhosis. (Kor J Gastroenterol 1999;34:338 - 344)