Aim: Endoscopic retrograde cholangiopancreatography ( ERCP) may be related with complications such as pancreatitis. C-reactive protein (CRP) can be provides reliable informations about post-ERCP complications and their severity. In our study, the role of CRP levels in the follow-up post-ERCP pancreatitis was investigated. Material and Method: 476 patients, whom performed ERCP for different indications, were retrospectively evaluated. 136 patients with measurement of serum amylase, lipase and CRP levels before and 1224 hours after the procedure were included the study. Alterations of these parameters in complicated and uncomplicated patiens were investigated. The role of CRP in the follow-up and prediction of severity of pancreatitis was investigated in 22 complicated patients with measurement of serum amylase, lypase and CRP levels 36-48 hours after the procedure. Pancreatitis were classified as mild, moderate, or severe. Results: Post-ERCP pancreatitis occured in 23 (17%) patients ( 9 mild and 14 moderate pancreatitis). The mean CRP levels (mg/l) at 12 to 24 hours were 23,5 +/- 24,18 in uncomplicated patients, and 59,2 +/- 44,87 in patiens with pancreatitis (p<0,05). The mean CRP levels (mg/l) at 12 to 24 hours were 30,8 +/- 14,24 in mild pancreatitis and 77,5 +/- 48,66 in moderate pancreatitis (p<0,05). The levels, respectively, at 36 to 48 hours were 37,7 +/- 20,73 and 84,6 +/- 48,31 (p<0,05). In the ROC curve analysis, significant cut-off values of CRP levels at 12 to 24 and 36 to 48 hours were 41 mg/l and 45 mg/l, respectively. Discussion: The follow-up of serum CRP levels after ERCP is a useful method for predicting and determining of severity of post-ERCP pancreatitis.