A chick-embryo-adapted canine distemper virus was propagated successfully for 64 passages in cultures of total chick-embryo tissues. As measured on the chorioallantoic membrane of live chick embryos, average virus titers of these passages ranged between 103.0 and 104.5 per ml of infected culture suspension. These titers are of the same order as those obtained with live-chick-embryo-grown virus. Identity of the tissue-culture-grown agent with the original CD virus was established by virus neutralization and by ferret immunization. Effective freeze-dried vaccines were produced with different passage levels of the tissue-culture-grown virus.