Abstract: OBJECTIVE To observe the auxiliary effects of low-dose cyclophosphamide on the patients with recurrent condyloma acuminatum (CA) and its influence on Th17 cells. METHODS Eighty cases of patients were randomly divided into control group and study group (40 cases each group). The control group was treated with CO₂ laser and 5-aminolevulinic acid photodynamic (ALA-PDT), once a week for 4 weeks continuously. The study group received cyclophosphamide 50 mg orally; a treatment course lasted for 7 d, and received 2 treatment courses with 3 days' interval. The recurrence of CA and HPV genotypes were compared. The subgroups of Th17 cells were investigated by flow cytometry; the protein content and mRNA expression of cytokines (IL-17 and IL-23) in peripheral blood were determined by ELISA and RT-PCR, respectively. The adverse reactions were recorded. RESULTS After treatment, the recurrence rate of 3, 6, 9 and 12 months of study group was 5.0%, 10.0%, 15.0% and 17.5%, respectively; were all lower than that of control group of 20.0%, 32.5%, 40.0% and 47.5% (P<0.05). The ratio of Th17 cells, the protein content and mRNA expression of IL-17and IL-23 were lower than those of control group. There were 9 kinds of HPV genotypes in the 80 cases, the clearance rate of HPV in study group was 90.0%, which was higher than that in control group of 70.0% (P<0.05). The incidence of adverse reaction rate was similar between the two groups. CONCLUSION Low-dose cyclophosphamide combined with CO₂ laser and ALA-PDT is effective and safe for recurrent CA.