The contagious nature of warts was proved 52 years ago when Ciuffo1 transmitted the disease with an ultrafiltrate. Particles thought to be viral have been visualized by electron microscopy from the papilloma and "Myrmecia" type warts. Myrmecia warts have the following characteristics, which some think help differentiate them from verruca vulgaris: Location—mostly plantar, palmar, pulp of digit Symptoms—pain Duration—89% present less than one year Number of lesions—rarely more than 5 (6%) Color—redness and swelling Surrounding callus—thick hyperkeratotic collar Edge—single and distinct Curettage—impression of plunging into a hole which suddenly exudes the wart Electron microscopy—virus-like particles The Myrmecia type wart was deliberately selected because of the reported greater number of viral particles as opposed to banal warts. This study demonstrates the isolation of the wart virus in tissue culture and its subsequent successful reinoculation into humans. Methods Two warts of the