The quality of five commercial monocalcium phosphates (MCP) and dicalcium phosphates with natural admixtures of hydrated and dehydrated forms was assessed on the basis of their crystalline phases determined by roentgenographic irradiation, Ca and P contents, and solubility in water, 2% citric acid, 0.4% HCl, and ammonium citrate solutions. The phosphates were used in diets fed between days 1 and 35 of life to 300 Hubbard Flex male broilers, 6 replications (cages) of 10 chickens per treatment. Performance indices, Ca, P and Mg retention, and the concentration of these elements in blood and bone ash, as well as the physical parameters of femur and tibia bones were measured. The content of P in phosphates varied between 17.7% and 23%, their solubility in citric acid and HCl solutions ranged between 89–99%. The roentgenograms indicated that phosphate No. 1 contained pure MCP; No. 2, MCP with admixture of anhydrous dicalcium phosphate (DCP); No. 3, DCP with an admixture of MCP; No. 4, dicalcium phosphate dehydrate (DDCP); No. 5, DDCP with an admixture of DCP. The type of phosphate used in chicken diets did not influence body weight or feed intake. Phosphorous retention, Ca and P in serum, and some bone parameters were better in chickens fed the diet containing pure MCP (P<0.01). Lower concentrations of Ca and P in bones and worse parameters of bone elasticity were found in chickens fed diets containing DDCP with DCP. In the biological experiment, the overall best results were obtained in chickens fed diets containing pure hydrated monocalcium phosphate.