OBJECTIVE: To evaluate the value of HPV L1 capsid protein applied in diagnosing high-grade cervical intraepithelial neoplasia (CIN 2/3) and cancer. STUDY DESIGN: A total of 232 patients with HPVpositive or abnormal cervical cytology higher than atypical squamous cells of undetermined significance (ASC-US) or both items positive were enrolled. HPV L1 capsid protein was detected with immunocytochemistry. The value of HPV L1 capsid protein applied in diagnosing CIN 2/3 and cancer was evaluated. RESULTS: The expression rate of HPV L1 capsid protein decreased with increasing CIN grade from CIN 1 to CIN3 and cervical cancer and was negatively correlated with CIN grade. The diagnostic value of HPV L1 capsid protein was higher in distinguishing CIN 2/3 and cervical cancer from CIN 1 than from normal cervical cells/chronic cervicitis cells and CIN 1. The specificity, accuracy, and positive predictive value (PPV) were higher in distinguishing CIN 2/3 and cervical cancer from CIN 1 than in distinguishing CIN 2/3 and cervical cancer from normal cervical cells/chronic cervicitis cells and CIN 1, and the false positive rate (FPR) was lower. CONCLUSION: HPV L1 capsid protein is suitable for distinguishing CIN 2/3 and cancer from CIN 1 rather than from low-grade CIN and lower conditions. © Science Printers and Publishers, Inc.