Objective To investigate the expression of human papillomavirus (HPV) L1 protein in lesional tissue of condyloma acuminatum and its clinical significance.Methods Forty-three patients with condyloma acuminatum were included in this study,and received CO2 laser therapy.Tissue samples were resected from the lesions of these patients at their first visit before treatment.Immunohistochemistry was used to determine the expression of HPV L1 protein in these samples.Follow up was carried out once every 2 weeks for 3 months to assess the recurrence rate and frequency in these patients after treatment.Results HPV L1 protein was detected in 83.72％ (36/43) of these tissue samples.The expression rate of HPV L1 protein decreased sequentially from patients infected with HPV 6/11,patients with both HPV 6/11 and 16/18,to those with HPV16/18 (x2 =17.90,P ＜ 0.01).During the 12 weeks of follow up,the recurrence rate was 69.77％ (30/43) with the average number of recurrence of 2.16.There was a sequential reduction in the recurrence rate and number from patients with strong expression of HPV L1 protein,to those with moderate expression,slight expression and negative expression (x2 =8.02,46.92,P ＜ 0.05 and 0.01,respectively).The expression intensity of HPV L1 protein was negatively correlated with the recurrence rate and frequency (rs =-0.429,-0.696,respectively,both P ＜ 0.01).Conclusion HPV L1 protein may serve as a helpful molecular biomarker for the prediction of prognosis and recurrence of condyloma acuminatum.