Cirrhotic patients are prone to having infections, which may aggravate hepatic encephalopathy (HE). However, the effect of infections on mortality in HE cirrhotic patients is not well described. The National Health Insurance Database, derived from the Taiwan National Health Insurance Programme, was used to identify 4150 adult HE cirrhotic patients hospitalized between 1 January 2004 and 31 December 2004. Nine hundred and eighty-five patients (23·7%) had one or more co-existing infections during their hospitalization. After Cox proportional hazard regression modelling adjusted by the patients' gender, age, and medical comorbidity disorders, the hazard ratios (HRs) in HE patients with infections for 30-day, 30- to 90-day, and 90-day to 1-year mortalities were 1·66 [95% confidence interval (CI) 1·42–1·94], 1·51 (95% CI 1·23–1·85) and 1·34 (95% CI 1·13–1·58), respectively. Compared to the non-infection group, the HRs of pneumonia, spontaneous bacterial peritonitis, urinary tract infection, sepsis without specific focus (SWSF), cellulitis, and biliary tract infection were 2·11, 1·48, 1·06, 2·21, 1·06, and 0·78, respectively, for 30-day mortality; 1·82, 1·22, 0·93, 2·24, 0·31, and 2·82, respectively, for 30- to 90-day mortality; and 2·03, 0·82, 1·24, 1·64, 1·14, and 0·60, respectively, for 90-day to 1-year mortality for HE cirrhotic patients. We conclude that infections increase the mortality of HE cirrhotic patients, especially pneumonia and SWSF.