Introduction: The measurement of Crohn’s disease activity is very useful in clinical practice as well as in clinical trials. However, traditionally used clinical scores lack precision. C-reactive protein has been known to be a sensitive marker for inflammation and tissue injury. Aim: The aim of the study was to correlate the CRP level with the disease activity and to assess its value in predicting Crohn’s disease severity. Material and methods: 89 consecutive patients (43 men and 46 women) with active or inactive Crohn’s disease were included in the study without any preselective criteria. CRP was measured and CD activity was calculated by means of Crohn’s Disease Activity Index (CDAI). Results: The median CDAI score was 224 (interquartile range 192-243) and the median CRP was 20 mg/l (interquartile range 5-38 mg/l, upper limit of normal 5 mg/dl). 49.4% of our patients had CRP >20 mg/l. CRP was significantly correlated with CDAI (p=0.000001). The diagnostic value for CRP predicting CDAI >220 was high. Conclusions: CRP appears to be useful to evaluate CD activity.