In the paper results of research of effect of particles zeolitic tuffs in the Kulikovsky deposit (Amur region) in size 10-50 microns on an organism of Wistar rats at oral introduction during 14 days are presented. Effect of particles of zeolites on a stomach, intestines, liver and kidneys of the rats is shown. All experiments with animals was performed with observance of the principles of humanity, set out in the directives of the European community (86/609/EEC) and with the Helsinki Declaration. Particles (10-50 microns) were received by crushing of a zeolitic tuff in the Kulikovsky deposit in a jaw crusher "Pulverisette 1" (Fritch, Germany) and sifted at first through a sieve with a diameter of cell of 50 microns, and then - through a vibration sieve with a diameter of 10 microns, and the average portion is left. Particles of this size in test there were more than 85%. A comparison of the experimental groups of rats, which zeolite particles of the Kulikovsky deposit introduced orally, with the control group showed no apparent distinctions in the histological structure of the tissue of the stomach, intestines, liver and kidneys in light microscopy. In experimental group was observed the infiltration by lymphoid cells and a hypertrophy of lymphoid follicles that is caused, apparently, by an immunogenicity of minerals. Also single necroses in tissues of kidneys and the raised of slime-formation in intestines are presented.