Objective:To determine expressions of HLA class I and CD80 in humanepithelial ovarian carcinomas(EOC) and the clinical significance.Methods:Expression of HLA class I was detected by immunohistochemical technique. Expression of CD80 mRNA was examined by reverse transcriptions-polymerase chain reaction(RT-PCR).Results:The positive rate of HLA classⅠ was 59.09%.CD80 mRNA was expressed on 9.09% of all 44 EOC tissues.HLA classⅠ expression rate in stage Ⅲ-Ⅳ was lower than that in stage Ⅰ-Ⅱ;in tumors of node-positive patients was lower than that of node-negative patients(P<0.05).In patiens with tumors expressing HLA class Ⅰ antigens,recurrence rate was lower than that in patients with tumors deficient in HLA class Ⅰ(P<0.01).In four patients with tumors expressing CD80 mRNA,recurrence did not occur,in contrast to patients with tumors lacking CD80 mRNA,in whom tumor relapse rate was 57.5%(P<0.05).Relapse ratein tumors deficient both HLA class Ⅰ and CD80 was significantly higher than that of tumors coexpression the two molecules.Conclusions:EOC cells may escapefrom the immune surveillance of the host through downregulating expressions ofHLA class Ⅰ and CD80.Evaluation of expressions of these surface immunoregulatory molecules may be helpful for judging prognoses of EOC patients and guiding immunotherapy. Objective: To determine expressions of HLA class I and CD80 in humanepithelial ovarian carcinomas (EOC) and the clinical significance. Methods: Expression of HLA class I was detected by immunohistochemical technique. Expression of CD80 mRNA was examined by reverse transcriptions-polymerase chain reaction ( RT-PCR) .Results: The positive rate of HLA class I was 59.09% .CD80 mRNA was expressed on 9.09% of all 44 EOC tissues. HLA class I expression rate in stage III-IV was lower than that in stage I-II; in tumors of node-positive patients were lower than that of node-negative patients (P <0.05) .In patiens with tumors expressing HLA class I antigens, recurrence rate was lower than that in patients with tumors deficient in HLA class I (P <0.01 ) In four patients with tumors expressing CD80 mRNA, recurrence did not occur, in contrast to patients with tumors lacking CD80 mRNA, in whom tumor relapse rate was 57.5% (P <0.05) .Relapse rate of tumors deficient both HLA class I and CD80 was significantly h igher than that of tumors coexpression of two molecules. Conclusions: EOC cells may escape from the immune surveillance of the host through downregulating expressions of HLA class I and CD80. Evaluation of expressions of these surface immunoregulatory molecules may be helpful for judging prognoses of EOC patients and guiding immunotherapy.