A total number of 180 one-day old unsexed Cobb broiler chickens were initially fed a control diet for six days, then were divided into six treatments (30 birds each), each treatment contained three replicates of ten birds, and the objectives were to evaluate the effects of single or combined supplementation of essential oils (EOs) and medium chain fatty acids (MCFAs) to broiler diets on productive performance.  The experimental treatments were as follows: 1- Chicks were fed the control diet (D₁₎.  2-D₁+ 0.1g thyme oil /kg diet.  3-D₁+ 0.2g thyme oil /kg diet.4- D₁+ 1g aromabiotic /kg diet. 5-D₁+ 1g aromabiotic/kg diet + 0.1g thyme oil/kg diet. 6- D₁ +1g aromabiotic/kg diet +0.2g thyme oil/kg diet. Results obtained could be summarized in the following: The higher significantly value of live body weight at 38 day and body weight gain during the period from 7 to 38 days were obtained for chicks  control diet. Inclusion of single or combined supplementation of EOs and MCFAs in the broiler diets at different levels had insignificant effects on feed intake during all periods studied. Chicks fed combined supplementation of EOs and MCFAs experimental diet (0.1g EOs/kg diet + 0.1% MCFAs) had best significantly feed conversion ratio during the period from 7-38 days of age compared with those fed the control diet and some other treatment. Combined supplementation of EOs and MCFAs to broiler diets caused significantly improves in performance index during the finisher period compared with those fed diets supplemented with MCFAs alone or the control. Chicks fed experimental diet containing 0.2g EOs/kg diet+ 0.1% MCFAs had significantly higher thymus and spleen% compared with those fed MCFAs alone, EOs alone and the control. Chicks fed diets supplemented with 0.2g EOs/kg diet+ 0.1% MCFAs had higher value of lymphocyte (lower values of eosinophiles, alanine aminotransferase, aspartate aminotransferase, total lipids, triglycerides and total cholesterol), Chicks fed diet containing 0.1g EOs/kg diet had higher intestinal pH, while; chicks fed diet containing 0.1% MCFAs resulted in the lower intestinal pH values (higher values of total count). The lower value of E.coli (significantly higher lactobacillus count) was obtained for chicks fed diet containing 0.2g EOs/kg diet+ 0.1% MCFAs. Chicks fed with 0.1g EOs/kg diet + 0.1% MCFAs had the highest economic and relative efficiency values during the period from 7 to 38 days.