We have initiated and established over 90 cell cultures from tissues of embroynic New Zealand rabbits. These cell lines show a very varied growth pattern when compared to cell lines initiated from human embryonic tissues. The type of medium used to grow the cells influences the chromosome stability of rabbit cells. Cultures initiated from kidney tissue rarely grow more than 10 passages unless the medium is supplemented with lactalbumin hydrolysate. In turn, analyses of metaphase chromosomes from the kidney cultures, revealed they were aneuploid as early as passages 15. Cultures established from skin and lung tissues will remain diploid at least 60 passages when grown on Eagle's Basal Medium supplemented with 10% fetal bovine serum. However, rarely do rabbit cell lines go into senescence.