Transforming growth factor-beta (TGF-beta) is a multifunctional peptide regulating several processes in ovarian cells. The growth of ovarian carcinoma cell lines (OVCAR-3, HTB-77, 2780 and CRL-1572) was reduced by TGF-beta in a dose related manner. The antiproliferative activity was not improved by combination with other biological response modifiers. Treatment with TGF-beta augmented the expression of interferon-gamma induced class I and II antigens of the major histocompatibility complex. The presentation of another antigen namely the tumor marker CA-125 on the cell surface was markedly reduced by TGF-beta.