['There exists a treatment challenge with periungual warts. Topical immunotherapy with diphenylcyclopropenone (DPCP) has recently been reported to be an effective treatment for recalcitrant warts, including periungual types.', 'We aimed to evaluate the effectiveness and preference of topical immunotherapy with DPCP in treating periungual warts.', 'Twenty-seven patients with periungual warts who were treated with DPCP immunotherapy (2007 through 2010; Dongguk University Ilsan Hospital, Goyang, Korea) were retrospectively recruited. Other treatment modalities were also used in some patients. Lesions were grouped into the types according to the following locations: proximal nail fold, lateral nail fold and hyponychium. Total and group clearance rates as well as treatment periods according to location and disease duration were evaluated. A patient questionnaire was performed to assess the satisfaction for the treatments in those who received multiple therapies.', 'Total success rates were 85% (by subjects) and 91% (by individual lesions). Success rate and treatment period for proximal nail fold type seemed more desirable than other locations. Success rate decreased and treatment period increased as disease duration increased. The questionnaire revealed a significantly higher satisfaction rate for DPCP immunotherapy than for cryotherapy and pulsed-dye laser.'] Is topical immunotherapy with diphenylcyclopropenone effective and preferred in the treatment of periungual warts?