In order to invest igate immune mechanism in pancreat i t is , following exper iments were tried. 1. Eleven ra ts were injected int raper i toneal ly 40 mg of dl-Ethionine every other day for 2 weeks. Serum amylase was elevated markedly and acinus of pancreas was fulled of zymogen granules. Latex agglutination tes t and double gel diffusion tes t were used to prove isoantibody of pancreas . Antibody appeared one month af te r the 1st injection and persis ted to about 5 months , and showed organ specificity. It d iminished on 295 days af te r the 1st injection, and the pancreas of this r a t was histologically normal . 2. Four ra ts of group A were injected in t ramuscu la ry wi th the homogenate of normal pancreas wi th Freund 's complete ad juvant once a week for 5 weeks. Four ra ts of group B were injected wi th the homogenate of dl-Ethionine injured pancreas wi th the adjuvant . Four ra ts of group C were injected only wi th the adjuvant . All ra t s of group B showed highly destroyed acinus in pancreas with marked fibrosis. But these changes were observed sl ightly in only 2 ra t s of Group A and 1 ra t of group C. In summary , the dl-Ethionine t reated pancreas resulted in severe changes in the pancreas of the recipient rats. I t was speculated tha t t r ea tment wi th dl-Ethionine caused a change in ant igenici ty of the pancreas and then severe pancreas damage occured.