A significant proportion of patients with cirrhosis can demonstrate elevated serum C-reactive protein (CRP) values which are not stimulated by bacterial infection. This may limit the clinical application of CRP determination in patients with cirrhosis. Therefore, we designed this prospective study to clarify whether serum CRP value could be used as an indicator of bacterial infection in patients with cirrhosis or not. A total of 129 sessions of admission (bacterial infection 46, bacterial infection and gastrointestinal hemorrhage 5, gastrointestinal hemorrhage 24, other causes 54) from 94 patients with cirrhosis were studied. Serum CRP value was determined on admission. The normal range of CRP value was < 6 micrograms/ml. The serum CRP values obtained on admission ranged from 3 to 232 micrograms/ml in patients with bacterial infection, 17 to 178 micrograms/ml in patients with bacterial infection and hemorrhage, < 1 to 44 micrograms/ml in patients with gastrointestinal hemorrhage, and < 1 to 54 micrograms/ml in patients with other causes of admission. Using the normal upper limit of CRP value as a cut-off value did not differentiate those patients with from those without bacterial infection. However, using the CRP value of 20 micrograms/ml which was obtained from receiver-operating characteristic curves could differentiate between two groups of patients (sensitivity 80.39%, specificity 80.77%, accuracy 80.62%). In conclusion, serum CRP determination can be used in the detection of bacterial infection in patients with cirrhosis. However, a new cut-off value should be applied.