This stuc1y was conducted to evaluate the therapeutic effect of immunotherapy on verruca plana. Forty-four patients with verruca plana were tried with dinitrochlorobenzene(DNCB) and diphenylcyclopropenone(DPCP) by topical application on the norinal uninvolved skin of the inner arms for sensitization and challenge. The lesions were challenged in weekly intervals after sensitization. The results obtained in this study are as follows. 1. Mean age of our patients was 20-year-old and sex ratio was about 1:2 (14 of male, 30 of female). 2. Tbe sites of the lesion weve face (60.9%), neck (7.2%), trunk (2.9%), arm (li3.0%), hand (11.6% ), leg (4.3% ). 3. Thirty two patients (72.7%) from 44 cases were completely cured after DNCB (81.3%) and DPCP (67%) treatment and iesions on younger patients showed a better response than those of of older patients(p<0.05). 4. There were no statistic relationship between duration of the lesions and therapeutic response. 5. Average challenge number after sensitization was 3.77 in DNCB, 2.26 in DPCP, respectively. 6. Sensitization rates in the cured patients were to treat verruca plana 94.7% (18/19) in DNCB, 76.9% (10/13) in DPCP, respectively. (Korean J Dermatol 1997;35(6): 1082-1087)