Abstract： Background Mutations in the cationic trypsinogen gene(PRSS1)have been detected in patients with hereditary pancreatitis(HP).This study investigated the prevalence of the R122H(c.365G＞A),A121T(c.361 G＞A)and D162D (c.488 C＞T)mutations or polymorphisms in the common,non-hereditary forms of chronic pancreatitis and in an HP family.Methods DNA was prepared from blood samples of 54 patients with chronic pancreatitis(35 alcoholic,17 idiopathic and 2 hereditary)and 120 normal controls.The PRSS1 genes were amplified by polymerase chain reaction (PCR) and their products were analyzed by sequencing and related clinical data were also collected.Results A new polymorphism(c.488 C＞T)of PRSS1 was found in 25 patients with chronic pancreatitis (including one affected member of the H P family)and six members of the normal controls.The C/T genotype was significantly increased in chronic pancreatitis(OR:16.379,95%CI:5.7522-52.3663),the frequency of c.488 C＞T change was in according with the Hardy-Weinberg equilibrium,but it doesn't affect the clinical phenotype.The commonly reported change of R122H (c.365G＞A)was not detected in any of the study subjects.c.361 G＞A was found in 2 affected members and one unaffected carrier in an HP family.One of the affected members of an HP family had c.361 G＞A mutation and polymorphism(c.488 C＞T)in the PRSS1 gene at the same time.The patient's clinical values(C3,C4,CA19-9 and HbA1c)were higher than those of the other patients with chronic pancreatitis.The two patients with HP developed diabetes mellitus and their father died with pancreatic cancer.Conclusion A new polymorphism(c.488 C＞T)in the PRSS1 gene is associated with chronic pancreatitis,but it did not affect the clinical phenotype while the A121T(c.361 G＞A)mutation in the gene shows a significant correlation in the patients with H P.