The influence of amino acids on the formation of particles of synthetic analogs of hydroxyapatites of renal calculi with different degrees of nonstoichiometry is investigated. It is demonstrated that the electrokinetic properties (the charge and the potential) and the dispersion composition of the synthesized hydroxyapatite sols depend on the Ca/P atomic ratio. The results obtained allow the assumption that, under the normal physiological conditions, free amino acids are natural inhibitors for the formation of renal calculi in the human organism.