Epithelial cells of human senile cataractous lenses from aged patients (over 60) were cultured in vitro. They began to grow from the 4th to 6th day of culture and formed typical epithelial cell sheets. The lentoid identified by immunochemical methods as a mass of lens fibers were found to develop at the terminal period of the primary culture. From the secondary passage of the culture, the growth potential of the cells decayed rapidly. It was also demonstrated clearly that the senile cataractous lenses still contained a small number of active epithelial cells exhibiting rather high growth and differentiation potentials, No signficant relationships between activities of epithelial cells and the condition of cataract have been observed so far.