Twenty-seven cervical condylomata were studied by morphological and immunohistochemical methods (peroxidase-antiperoxidase technique according to Sternberger, with some modifications). The antiserum was obtained from rabbits immunized by human papillomavirus virions; 37% of condylomata stained positively and the koilocytotic cells showed a dark brown nuclear stain. This technique, not particularly useful for diagnostic purposes, could be employed to obtain better understanding of the natural history of these cervical neoplasias.