The study was conducted to determine the effects of supplemented thyme oil extract and thyme water extract, the water soluble fraction of thyme extract, on fattening performance, blood parameters, oxidative stress and DNA damage in Japanese quails. Two hundred sixteen chicks were divided into four groups: control (no antibiotic or thyme extracts (I), flavomycin (II), thyme oil extract (III) and thyme water extract (IV). Groups II and III received 1 g/kg flavomycin as an antibiotic and 2.5 ml/kg thyme oil extract, respectively. Birds in group IV received 100 ml/l of thyme water extract in their drinking water. There were no significant differences in liveweight between the treatment groups, but feed intake differed (P<0.01) at 0-5 weeks of age. Results showed that thyme extracts decreased feed consumption during the experiment. Similarly, the survival rate differed significantly (P<0.01) between groups; the lowest was in antibiotic group. The levels of plasma cholesterol, triglyceride, high density lipoprotein, very low density lipoprotein and alkaline phosphates were similar in the four treatments. The highest rate of total oxidant status and total antioxidant response were found in group III, the lowest rate of DNA damage in the thyme oil (III) and thyme water extracts (IV) groups. It was concluded that supplementing thyme extract products in the diet of quails at the doses studied does not lead to a negative effect on the growth performance of the birds. Supplemented antibiotic caused an elevation in the oxidative stress index and in DNA damage.