In bovine oviduct cells 17beta-oestradiol can induce the synthesis of leukaemia inhibitory factor (LIF), a glycoprotein essential for embryo implantation. Therefore substances which are structurally similar to 17beta-oestradiol and possess oestrogenic activity may also modulate LIF synthesis and influence the reproductive process. We used primary cultures of bovine and human oviduct cells (epithelial cells:fibroblasts 1:1) to compare the effects of 17beta-oestradiol, phyto-oestrogens (genistein, biochanin A, daidzein, formononetin, and equol) and xeno-oestrogens [polychlorinated biphenyls (PCB): trichlorobiphenyl, 4-hydroxy-trichlorobiphenyl and 4-hydroxy-dichlorobiphenyl] on LIF synthesis. Immunoreactive LIF-enzyme-linked immunosorbent assay was used to determine the concentration of LIF in the culture medium. Similar to 17beta-oestradiol, genistein (0.02-2 micromol/l) induced LIF synthesis in bovine oviduct cells in a concentration-dependent manner. Equol, biochanin A and daidzein (2 micromol/l), 4-hydroxy-trichlorobiphenyl and 4-hydroxy-dichlorobiphenyl (0.01-10 micromol/l) but not formononetin (2 micromol/l) also induced LIF synthesis in bovine cells. Phyto-oestrogens and xeno-oestrogens also induced LIF synthesis in human oviduct cells (P < 0.05). The stimulatory effects of PCB, phyto-oestrogens and 17beta-oestradiol were blocked by ICI 182,780 (1 micromol/l). Moreover, 17beta-oestradiol, 4-hydroxy-trichlorobiphenyl, 4-hydroxy-dichlorobiphenyl, genistein, tamoxifen and ICI 182,780 displaced [(3)H]17beta-oestradiol from cytosolic oestrogen receptors in bovine oviduct cells. These results suggest that phyto-oestrogens and PCB mimic the effects of oestradiol in inducing LIF synthesis by bovine and human oviduct cells and that these stimulatory effects are oestrogen receptor-mediated. Environmental oestrogens act as endocrine modulators/disrupters and may induce deleterious effects on the reproductive process by influencing LIF synthesis in a non-cyclic fashion leading to tubal infertility.