Abstract： Objective Comparative studies on the influence of human adult pancreas of different blood group used as antigen substrate upon the specificity and sensitivity of ICA assay with immunohistochemical method.Methods The serum specimens of 24 cases of type 1 diabetic patients with positive ICA testing and 23 cases of normal subjects with negative ICA testing were assayed for the ICA with immunohistochemical method using human pancreas of different A,B,O and AB blood group as the antigen substrate.Results Using human pancreas of O blood group as control, three cases of pancreases of A blood group and B blood group as well as two cases of pancreases of AB blood group were used as antigen substrate for assaying the ICA. The results showed that the specificity and sensitivity of ICA assay of 24 ICA positive sera were basically consisent with that of 23 ICA negative sera, while the false positive or false negative result was not seen.Conclusion The results of this paper demonstrated that the human pancreas of A, B or AB blood group may be used as the pancreas of O blood group for assaying ICA with immunohistochemical method, and human pancreas of different blood group as the antigen substrate for assaying ICA would not influence the specificity and sensitivity of the assay.