The first results of the use of the Allium test for estimation of toxicity of bottom sediments in the Yenisei River and the effect of external ?-radiation under laboratory conditions are presented. The effect of stimulation of the onion root growth, i.e., the absence of toxicity was discovered in toxicological experiments using bottom sediments and under external ?-radiation. The stimulating effect of radiation on the growth of onion roots limits the use of the Allium test for testing samples from the Yenisei River ecosystem in the zone subjected to the impact of radioactive discharges from the Mining and Chemical Combine.