As an initial step toward better understanding of the molecular mechanism of estrogen-dependent growth in myoma, an optimal primary cell culture condition has been developed and examined by this study. Myoma and myometrium were cultured by two different methods. Culture stability and $E_2$-responsiveness in stable culture were studied. The culture of digested tissue pieces(Method 2) was found to be a stable culture method for the myoma and myometrium showing a favorable response to estrogen. mRNA expression of PR, IGF-1 and IGF-1 receptor genes was enhanced by $E_2$. The gene responses to $E_2$ were higher in myoma compared with myometrium. Moreover, these responses were more expressive in tissues than in the surrounding cells in primary culture of normal myometrium and myoma, implying a vital role of cell communication through the extracellular matrix in maintaining the estrogen-responsiveness. The development of an improved cell culture system for myoma provides an in vitro tool to further investigate the basis of the tumor formation.