The addition of estradiol alone to oviduct cell cultures was sufficient to induce ovalbumin synthesis, detectable both by immunofluorescence and immunoprecipitation of newly synthesized protein. Most cells stained positively for ovalbumin indicating that the culture conditions promoted the growth of the ovalbumin synthesizing tubular gland cells relative to other cell types. The rate of ovalbumin synthesis was lower than that expected in vivo but as high as or higher than that found in organ culture. In tissue culture ovalbumin gene expression was under the direct influence of estrogen. Previous work showed that estrogen did not stimulate rapid proliferation of oviduct cell cultures (S. S. Seaver, J. van der Bosch & G. Sato, Exp cell res 155 (1984) 241) [5]. Therefore further experiments were done in vivo to correlate the effects of different hormonal regimes on oviduct growth and ovalbumin synthesis. In several instances the hormones affected oviduct growth differently than they affected ovalbumin synthesis. However, there was a strong correlation between the ability of a hormonal regime to stimulate oviduct growth in vivo and the ability of the serum from those chicks to stimulate oviduct cellular proliferation in culture. In vivo estrogen also stimulates oviduct growth by very different mechanisms than it stimulates the expression of the egg white protein genes.