The aim of the study was to undertake comparative evaluation of chemical composition and physical properties of the fat tissue of the Romanov sheep breed on condition of separate and joint use of natural additives "Glaukonit" and probiotic "Biogumitel". A positive effect of their use has been established. The young stock consuming the tested additives at the dose of 0,1 g per 1 kg of live weight surpassed on weight of internal fat and carcass fat of control analogs by 0,04-0,21 kg (9,09-47,73%) and 0,12-0,29 kg (6,38-15,44%). The content of dry matter and chemically pure fat was higher in the fat tissue of the ram hogs of experimental groups in internal fat by 0,03-0,72% and 0,20-0,60%, subcutaneous fat by 0,02-0,08% and 0,04-0,15%; intermuscular fat by 0,09-0,22% and 0,05-0,13%, respectively. Internal fat had the greatest energy value, intermuscular fat had the lowest energy value, and subcutaneous fat took an intermediate position. In all cases, the ram hogs of experimental groups were in the lead and surpassed the control on the energy value of internal fat by 0,08-0,25 mJ (0,23-0,70%); intermuscular fat by 0,01-0,04 mJ (0,03-0,12%); subcutaneous fat by 0,02-0,06 mJ (0,06-0,18%). An increase in the iodine value in the fat samples of the experimental groups was established. All changes occurring in the fat tissue of young sheep were within the regulatory limits and corresponded to the breed characteristics. At all stages of research the maximum effect was achieved due to by joint use of tested additives.