A commercial preparation of charcoal-stripped adult bovine serum was used to culture MCF-7 cells in estrogen-free media. Use of this stripped adult bovine serum represents an alternative to calf serum which is in more limited supply, and saves charcoal-stripping of serum in the laboratory, which can be a rate-limiting step in the preparation of materials for estrogen-free tissue culture. MCF-7 cell proliferation was controlled by estrogens, epidermal growth factor (EGF) and lithium chloride in adult bovine serum as well as in standard media prepared with charcoal-stripped calf serum, and approximately the same fold-increase in response to the tested agents was observed in the two sera. Although the growth rates were lower in media prepared with adult bovine serum, MCF-7 cells in both media exhibited the same sensitivities in dose-responses to these three mitogens. Levels of estrogen and progesterone receptors, and the magnitude of estrogen-dependent stimulation of the progesterone receptors, were similar in cells maintained in both sera. Therefore, a commercially stripped adult bovine serum can be used to replace calf serum in the study of estrogenic responses and the control of proliferation in MCF-7 breast cancer cells.