Herbs have some medical properties and pharmacological activities that could help in improving productive, pharmacological, immunological performance and/ or plasma biochemical parameters of poultry. Medicinal and aromatic plants and their by-products are preferable as feed additives and growth promoters. conducted to study: The effects of fennel seeds,thyme dried leaves and partially replacing of yellow corn (YC) with dill or parsley by-products incorporation to broiler diets on growth performance, mortality rate, carcass parameters, bacteria enumeration, intestinal pH, blood parameters and economical efficiency.