We evaluated the efficacy of squaric acid dibutylester (SADBE) contact immunotherapy for the treatment of warts on a series of 188 children. Included in the study were those children who satisfied at least two of the following criteria: single or multiple sites with several warts, warts resistant to repeated medical and/or surgical treatments, recurrent multiple warts, and patient or parent refusal to undergo destructive or surgical treatment. Excluded from the study were children with single warts or with flat warts located exclusively on the face and children less than 2 years of age. Treatment consisted of twice weekly applications of serial dilutions of SADBE (0.03-3%) for no more than 10 weeks. Of the 148 children who completed the study, 124 (84%) showed complete clinical resolution with no significant side effects. Of those with total clinical resolution, 101 completed a 24-month follow-up with no relapses. Twenty-four (16%) children were nonrespondent. No apparent correlation between treatment response and age, gender, anatomic site, lesion type, or atopy was found. Contact immunotherapy with SADBE is a relatively safe and effective alternative treatment in the management of multiple and resistant cutaneous warts in children.