38 children with chronic osteomyelitis of the jaws were observed during 2008-2015. It was detected that in patients with chronic osteomyelitis of the jaws were observed reduction of MD content till 112%, on background of reduction of CA till 21, 1% (P>0, 001) and was increased of correlation MDA/CA 10 times. At that content of MAM₂₅₄ and MAM₂₈₀ was correspondingly composed of 179, 16% and 100% as well as coefficient resistance of protein 75, 9% (P<0, 001) from index of control group. It was detected that between content of MDA and fatty acids in sick children’s blood with chronic osteomyelitis of the jaws were observed higher correlation but with saturated fatty acids were average one. Catalase activity is highly correlated both with saturated and unsaturated fatty acids.