Oestrogens can regulate immune functions, and due to this females have more effective immune responses than males. Oestrogens and anti-oestrogens enhance T-cell-dependent antibody production of B cells in vitro. The cytokine mediators which are behind oestrogen and anti-oestrogen induced effects are not yet known. The authors studied whether anti-oestrogens (tamoxifen and toremifene) can regulate PMA-induced cytokine production of B-, T- or myeloid cell lines. Anti-oestrogens, tamoxifen and toremifene, stimulated overall cytokine production on a B-cell line (Ball), whereas on a T-cell line (Molt-4) tamoxifen stimulated IL-1 beta, IL-6 and IFN-gamma production and toremifene inhibited it. Anti-oestrogens did not have any significant effect on cytokine production of myeloid cells.