This study was done to evaluate and investigate the effects of using different drugs on reducing the 
frequency and severity of Post- ERCP pancreatitis. The study was done on 90 randomized patients 
with extrahepatic cholestasis and divided into three groups. Post ERCP pancreatitis was diagnosed by
laboratory investigations, ultra-sonography and triphasic abdominal CT criteria of pancreatitis. The 
results of this study showed that there was a statistically significant difference in the percentage of 
knife precut between the studied groups. There was a statistically significant difference in the degree 
of post ERCP pancreatitis during comparison the control group with each studied drug group, in 
which allopurinol has a protective role in the occurrence of post ERCP pancreatitis by regression 
analysis. It is concluded to use allopurinol before ERCP procedure.