This study aimed to evaluate the effects of a mixture of olive, laurel and rosemary leaf powders, on performance and egg quality, the oxidative state and biochemical, immune, and intestinal morphophysiological parameters of laying hens. One hundred Lohaman Brown hens (28 weeks old) were equally assigned to two groups (n. 50) corresponding to a basal control diet (CON) or the diet supplemented with 6g/kg feed of leaf powder mixture (LPM) containing olive, laurel and rosemary leaves (1:1:1), for 8 weeks. Egg traits, oxidative status, biochemical indices, immune response, cecal short chain fatty acids (SCFAs) and intestinal morphological characteristics were evaluated at the end of the experiment. The results indicated that body weight and egg quality parameters were not influenced by LPM. However, LPM improved (P<0.01) the oxidative status and the immune system, total protein (P<0.05) and HDL cholesterol (P<0.01) and decreased total cholesterol (P<0.01) and LDL cholesterol (P<0.05), as compared to the CON. Aspartate amino transferase (AST), alkaline phosphatase (ALP) and alanine amino transpherase were significantly better in the LPM than in the CON group. A significant increase (P<0.05) of SCFA content established in the caecum and in villi height and crypt depth in both duodenum and ileum LPM treated hens was observed.