Observation was made of the influence of natural zeolite (clinoptilolite) supplement in food on 134Cs excretion and distribution after oral internal contamination of laboratory brown rats. After diet administration with 2.5, 5, and 10% zeolite supplement the 134Cs elimination in droppings increased and the radionuclide deposition in liver, kidneys and femoral musculature decreased. The zeolite decontamination effects were observed with preventive administration, as well as with sorbent administration from the 24th hour after a single internal contamination.