To compare the efficacy and safety of CO₂ laser plus 5-aminolevulinic acid (ALA) photodynamic therapy (PDT) with CO₂ laser for the treatment of multiple condyloma acuminatum (CA), 120 patients with multiple CA were allocated into two groups — combined group (CO₂ laser plus ALA-PDT, n = 60) and CO₂ laser group (CO₂ laser plus placebo-PDT, n = 60). After CO₂ laser, a 20% ALA or a placebo solution was applied to the CA area 3 h before illumination with red light (635 nm, 100mW/cm2, 80 J/cm2T. The treatment was repeated seven days after the first treatment if the lesions were not completely resolved. The complete response rate, recurrence rate and adverse effects in the two groups were analyzed. After two treatments, the complete response rates in the CO₂ laser group and combined group were 100% (509/509) and 100% (507/507) in the CA (p > 0:05), respectively. The recurrence rates in the CO₂ laser group and combined group were 44.9% (229/509) and 10.6% (54/507) in the CA (p < 0:05), respectively. The adverse effects in CO₂ laser group was more than that in combined group. The combined group is a more effective treatment for multiple CA compared with CO₂ laser group. T/S. Style the highlighted text as abstract.