This study investigated the effects of dietary supplementation with phytogenic feed additives, Digestarom® 1317 and thyme, on the growth performance, oxidative stress and intestinal microflora in broiler chickens. A total of 120 1-day-old broiler chicks were randomly allocated into four groups with three replicates per treatment and 10 birds per replicate. The dietary treatments were the basal diet (control), basal diet with Digestarom® 1317 at 1.5 g / 10 kg diet, basal diet with Digestarom® 1317 at 3.0 g /10 kg diet and basal diet with thyme at 100 g / 10 kg diet. The results revealed that 1.5 g/10 kg Digestarom® 1317 increased the body weight significantly compared with the higher dose of Digestarom® 1317 or thyme. Digestarom® 1317 and thyme significantly increased the phagocytic activity and index, the antioxidant enzymes activities and significantly decreased protein nitrosylation. Thyme significantly increased the serum protein pattern, whereas both phytogenic additives non-significantly increased the level of liver-specific enzyme. The addition of phytogenic additives ameliorated the intestinal microflora via the reduction of coliforms at the ages of 14 and 28 days and via the fortification of beneficial gut flora, such as lactobacilli. This study concludes that Digestarom® 1317 at 1.5 g / 10 kg had a growth promotion effect and that Digestarom® 1317 and thyme had antioxidant, immunostimulant and gastrointestinal health effects. The beneficial effects of the addition of Digestarom® 1317 and /or thyme to the broiler diets resulted in the economical production of good quality white meat with no harmful residues.\nKeywords: Digestarom® 1317, thyme, protein nitrosylation, growth promoter, antioxidant, gut flora.