Std. feed mixt. and its 2 Hg-contg. modifications optionally with the test formulation were used sep. to feed 3 group of hens kept in cages. The concn. of Hg introduced into the feed as MeHgCl was 5 mg/kg of the mixt. The formulation was added in amt. of 3%. After 8 weeks of the test, concn. of Hg and Se in eggs, liver, kidneys and muscles in each group of hens were detd. by at. absorption spectrometry. Consuming the poisoned food by hens resulted in an increase in the Hg concn. in eggs, muscle, liver and kidneys by 1010, 650, 222 and 60 times, resp., in relation to the control group of hens. In both group of hens (poisoned and detoxified), a decrease in the concn. of Hg in eggs, muscle, liver and kidney by 2, 10, 33 and 35%, resp. (relative to group of hens poisoned) was obsd. At the same time, an increase in Se content was 30-100% in relation to the control group. Addnl., a 6 month test with the examd. formulation as 10% additive to the ground grain used as food for breeding hens in farms was carried out. The Hg content in eggs before and after the test showed a redn. by 22.5%. The Se content increased by approx. 59%.