Recalcitrant viral warts are a troublesome therapeutic problem. Immunotherapy with the universal allergic contact sensitizer diphencyprone (DCP) has been used successfully in such cases. We have reviewed our experience of the use of DCP in the treatment of resistant hand and foot warts during an 8-year period. Sixty patients were sensitized to DCP during this time; the median duration of warts was 3 years. Twelve patients defaulted from treatment. Of the remaining 48 individuals, 42 (88%) cleared of all warts. The median number of treatments to clear was five (range one to 22) and the median time to clear was 5 months (range 0.5-14). Adverse effects occurred in 27 of 48 patients (56%), most commonly painful local blistering (n = 11), blistering at the sensitization site (n = 9), pompholyx-like reactions (n = 7) and eczematous eruptions (n = 4). Three of those who defaulted did so due to side-effects, one became pregnant and eight dropped out for unknown reasons. Three of the 48 patients who cleared or had at least six treatments also discontinued DCP therapy due to side-effects, but most tolerated treatment well. Twenty-five patients were followed up for periods of 1 month to 8 years (median 2 years) and none had a recurrence. DCP immunotherapy is an effective option for the treatment of recalcitrant viral warts but patients must be motivated to attend for sequential applications and must be warned about potential uncomfortable side-effects.