Human papillomavirus-induced plane warts most often occur in the second decade of age. Afterward, they either spontaneously regress or are eradicated in the course of various treatments. As proved by in vivo and in vitro tests as well as clinical observations, they most often affect and persist longer in immunocompromised hosts. In this work it was confirmed that specific-ie, anti-HPV-directed, cell-mediated immunologic response plays a role in spontaneous regression of plane warts and that preservation of nonspecific immunity is prerequisite for spontaneous regression of plane warts.