The effect of synthetic zeolite was investigated on the development of tibial dyschondroplasia in young broilers fed diets in which the dietary levels of calcium, phosphorus, and chloride ranged from adequate to deficient. In the first two experiments the calcium level was maintained at .65% and four combinations were fed of .30% and .15% chloride and .75% and .50% phosphorus with and without 1% zeolite. Feeding the high phosphorus diet caused a high incidence of tibial dyschondroplasia that was lowered by feeding 1% zeolite. In both experiments the feeding of zeolite at a low level of dietary phosphorus caused a significant lowering of 16-day weight and bone ash. In the third experiment, when diets containing all combinations of .65% and .80% calcium and .50% and .60% phosphorus were fed, the addition of 1% zeolite caused a significant lowering of the 16-day weight, bone ash, and incidence, score, and percentage severe tibial dyschondroplasia. Once again as in the previous two experiments, there was a significant interaction between dietary phosphorus level and zeolite and 16-day weight and bone ash. Feeding zeolite significantly decreased phytate phosphorus retention.