Three experiments were conducted with Hy-Line W-36 laying hens housed in individual wire cages in open type houses. The first and second experiments were designed to investigate the effects of sodium chloride and sodium bicarbonate fed at two levels of dietary total phosphorus (.30 and .60%). The third experiment was designed to study the interrelationships between age and sodium source. Supplementing sodium chloride at two levels (.37 and 1.11%) did not effect hen performance, except that egg production was better at the lower NaCl. Egg production was greater when .60 rather than .30% dietary phosphorus was fed. Egg specific gravity and egg weight were decreased at the lower dietary phosphorus. The addition of 1.6% sodium bicarbonate in the sodium chloride-free diets was deleterious to hen performance in all experiments. High mortality was observed in both experiments in which hens were fed diets containing high sodium and low chloride. Plasma calcium and phosphorus levels were significantly depressed in hens fed diets containing the lower phosphorus. Blood pH, base excess, bicarbonate, and total carbon dioxide were significantly increased by sodium bicarbonate supplementation, and these values were found to be inversely related to dietary phosphorus levels.