Experiments were conducted to determine the effect of feeding a high (19.6%) or low (7.7%) fiber diet to meat- and egg-type chickens during the last 6 wk of their growing period followed by a high (12.4%) or low (6.2%) fiber diet during the breeding period. The addition of finely ground wheat straw at 40% of the ration during 15–21 wk of age resulted in a significant reduction in feed consumed, exclusive of the added fiber, per hen–day in both strains and a reduction in body weight gain per bird, but it had no effect on feed conversion efficiency. The addition of fiber also resulted in a significant increase in weight (and size) of various components of the digestive system in both strains when this was prorated to body weight. The carryover effects of feeding high fiber during the growing period were manifested by increased rate of lay and body weight gain in both strains, irrespective of the breeding period diet. However, pre-treatment on high fiber growing diet resulted in increased feed efficiency of both strains of hens fed a low fiber breeding diet, but not of the hens fed a high fiber breeding diet. The high fiber rations (20% wheat straw) fed during the breeding period depressed rate of lay and feed efficiency but did not affect the weight, quality, fertility or hatchability of the eggs. Mortality during the growing and breeding periods was not affected by the high fiber diet. Apparently chickens are capable of a high degree of anatomical and physiological adaptation to compensate for variation in nutrient concentration of their diet. Such adaptation during the growing period showed some beneficial effects on breeding period performance in meat- and egg-type chickens.