Although information is available on thein vit-roproperties of lens epithelia of young adult animals from several species, few, if any reports document the conditions required for the initiation and long-term culture of lens epithelium from animals beyond their medium life-span. We report here on the conditions required for the culture of lens cells from an 8 year old rabbit. New Zealand White rabbits have a median life-span of approximately 7 years. Primary culture was initiated in MEM supplemented with 10% rabbit serum. Cells reached confluency within 25 days, responded to serum in a dose dependent manner and had an average doubling time of 23 h during the logarithmic growth phase. Cells increased in number in a dose dependent manner when insulin, insulin growth factor, epidermal growth factor (EGF), or fibroblast growth factor (FGF) was added to the culture medium. Thus, lens epithelia from this very old rabbit retained the ability to respond to highly purified growth factors. Cells exposed to a medium supplemented with insulin, EGF and FGF showed a five-fold increase in number at day 7 of culture, a value exceeding that brought about by the individual growth factors. An examination of chromosomal preparations indicated that the cells were aneuploid. Whether the aneuploidy was acquiredin vitroor is a normal adjunct of aging in the lensin vivois unknown. Proteins extracted from this line contained polypeptides that migrated to the position of and had apparent molecular weights of lens proteins.