Medicinal herbs, which contain great quantity of phenol ingredients, are of interest as potential sources of natural antioxidants. Representatives of genus Thymus L. (Lamiaceae) contain variable composition of essential oils and flavonoids. Phenol constituents of the thyme (Thymus vulgaris L.) essential oil, timol and carvacrol, flavonoids such as luteolin, naringenin, cirsiliol etc, already have been confirmed as components with expressive antioxidant activity. In this work inhibitory activity of wild thyme extracts samples on thermal autooxidation has been investigated during the period of 20 days. Ether and ethyl acetate extracts were prepared from 8 Macedonian Thymus species, in concentration range of 0.5, 1.0 and 5.0%. In portions of lard the same quantity of each extract was added (0.04%) and incubated at 60oC. The intensity of lipid peroxidation has been investigated with the peroxide quantity determination, in 3 days intervals, with iodometric method. The obtained values were compared with the inhibitory activities of BHT, BHA, a-tocopherol, caffeic acid, luteolin and luteolin-7-glycoside. Extracts of some wild thyme samples (5.0%) showed good inhibitory activity and represented an interesting subject for further investigations of the antioxidant effect.