Expression of blood group antigens in normal, displastic and tumoral uterine cervix from 35 hysterectomised women with carcinoma of the cervix was investigated; the results were correlated with patients' ABH phenotype and secretor status. We used an indirect immunoperoxidase technique and a panel of monoclonal antibodies and lectins directed against different antigenic specificities. Anomalous expression of blood group antigens in premalignant lesions from cervix was found. Partial loos of expression of blood group antigens and some lectins in different grades of cervical intraepithelial neoplasia, and a total loss of expression in CIN III and in infiltrating carcinoma of the cervix from secretor patients was revealed. The findings herein described confirm the importance of these antigens as tumour markers and they might be useful for the study of cervical carcinogenesis.