The major histocompatibility complex probably plays a crucial role in the efficacy of the cellular immune response against virally infected cervical diseases. Therefore, the allele-specific histocompatibility-related leukocyte antigens (HLA) class I and II expression on normal (n = 10), premalignant (n = 25), and malignant cervical tissue (n = 30) was investigated. No alterations in monomorphic or locus/allele-specific HLA class I or II expression were observed in normal and premalignant epithelial tissue. In cervical carcinomas, however, a reduced expression of HLA class I antigens was present in 70% of the cases, comprising a monomorphic class I loss in 20%, and an allele-specific loss in 50% of HLA-A2-, 66% of A3-, 56% of Bw4-, and 37% of Bw6-positive patients. De novo expression of class II antigens was observed in 80% of the cervical carcinomas, with the sublocus products being expressed in the order HLA-DR > HLA-DQ > HLA-DP. The authors' results show that alteration in HLA expression is a process confined to malignant cells, which may allow tumors to evade immune surveillance. In addition, these findings have to be considered as new strategies of immunotherapy using cytotoxic T lymphocytes are developed.