A number of human papillomavirus (HPV) type 16 proteins have recently been identified in human cervical carcinoma cell lines using polyclonal antisera against papillomavirus gene products expressed in Escherichia coli. E7 protein has been found to be the most abundant papillomavirus protein in these cells. Here we describe a panel of monoclonal antibodies recognizing a 15K Mr non-glycosylated cytoplasmic HPV-16 E7 protein. One of the antibodies cross-reacted with HPV-18 E7 protein.