This study was conducted at the experimental farm, Department of Animal Production , College of Agriculture , University of Tikrit for the period from 7/10/2018 to 15/12/2018. Sixteen Awassi lambs with an average body weight of 27kg and aged about 6—7-months were used in this investigation. The lambs were randomly assigned into four groups. Each group has 4 lambs the lambs were placed in individual cages (1 x 1.5 m².) and the aim of this study to investigation the effect of supplementing linseed oil on chemical composition and some fatty acids of Awassi chilled and frozen sheep meat,the results showed high significant differences in frozen period in moisture content of meat compared with chilled period it was ( 70.90 and 66.82)% respectively , and the chilled period conducted high significant differences than the frozen period in fat content ( 9.39 and 8.15)% respectively. About the effect of linseed oil on fatty acids, frozen period conducted high significant differences in Oleic it was 33.59 % while the frozen period conducted a high significant differences in Linoleic and Arachidonic acids it was ( 4.88 and 1.19)% respectively. The interaction between chilled period and treatments, the first and second treatment conducted high significant differences on Oleic acid also first treatment was high in Linoleic Acid percentage. While for the interaction between frozen period and treatments, the fourth treatment was high in Oleic and Linolenic Acid percentage, the first treatment was high in Linoleic Acid percentage it was (5.22)%.