Two experiments were conducted to examine the effect of oxytetracycline-supplemented diets on mortality of young endangered masked bobwhite quail (Colinus virginianus ridgwayi). Inclusion of oxytetracycline at 200 g per ton in the feed for 6 weeks resulted in a marked, significant reduction in mortality of young masked bobwhite quail raised in captivity. Including the antibiotic in feed during the first week of life reduced mortality as effectively as feeding it for a longer period.