The aim of this research effort is to continue the study of the carcinogenic potential of Herpes virus II in the mouse uterus. Squamous epithelial lesions of dysplasia and early invasive lesions have been demonstrated in a large proportion of the animals as well as lethal invasive carcinoma by the continued application of formalin-inactivated Herpes virus II by both cytological and histological methods. These lesions resemble those encountered in the human cervix. Planned studies include testing Herpes virus II inactivated by other methods including fractionation of the viral material, evaluation of any carcinogenic activity of Herpes virus I. Immunological aspects of the problems will be studied relating to antigen-antibody titers of the mice and the possibility of developing tumor immunity.