OBJECTIVE: To determine the efficacy of duct tape compared with placebo in the treatment of verruca vulgaris. DESIGN AND SETTING: A randomized placebo-controlled trial in 3 primary schools in Maastricht, the Netherlands. PARTICIPANTS: One hundred three children aged 4 to 12 years with verruca vulgaris. INTERVENTIONS: Duct tape applied to the wart or placebo, a corn pad (protection ring for clavi), applied around the wart for 1 night a week. Both treatments were applied for a period of 6 weeks. Patients were blinded to the hypothesis of the study. MAIN OUTCOME MEASUREMENT: Complete resolution of the treated wart. RESULTS: After 6 weeks, the wart had disappeared in 16% of the children in the duct tape group compared with 6% in the placebo group (P = .12). The estimated effect of duct tape compared with placebo on diameter reduction of the treated wart was 1.0 mm (P = .02, 95% confidence interval, -1.7 to -0.1). After 6 weeks, in 7 children (21%) in the duct tape group, a surrounding wart had disappeared compared with 9 children (27%) in the placebo group (P = .79). Fifteen percent of the children in the duct tape group reported adverse effects such as erythema, eczema, and wounds compared with 0 in the placebo group (P = .14). CONCLUSION: In a 6-week trial, duct tape had a modest but nonsignificant effect on wart resolution and diameter reduction when compared with placebo in a cohort of primary school children.