Bobwhite quail (Colinus virginianus) received dietary mirex in concentrations of 1, 20 and 40 ppm to investigate reproductive effects of long term exposure to this chemical. Residue analyses of Fo generation breeders indicated that male adipose tissue contained approximately 10 times the mirex level in the diet. Elimination of mirex in females probably was facilitated by egg laying, which reduced mirex buildup in adipose tissue to five times the dietary level. Both sexes were noted to concentrate mirex in fat and breast tissue in direct proportion to the intake of dietary mirex. Eggs collected from Fo generation breeders were not affected deleteriously by mirex as measured by embryo survival to 3 weeks, and thenumber of eggs failing to hatch. Indeed, increased rates of egg fertility and hatchability were associated with higher dietary concentrations. Chick survival data was obtained in Fp and F1 generation hatchlings from hatching through 2 weeks. No chick mortality attributable to pesticide stress was detected in either group of birds. Eggs collected from F1 generation breeders that received 1 ppm were not affected harmfully as measured by embryonation, embryo survival, and hatchability rates. Comparison of residues in wild bobwhites with residues in our experimental findings indicates mirex is apparently not affecting deleteriously reproductive success of wild quail.