Abstract: An experiment was conducted to study the effect of adding three types of feed additives avizyme, phytase, a mixture of condiments at two levels or their combination to corn-soybean meal based diets. Dietary treatments included feeding a control corn-soybean diet, while in the other diets, the control diet was supplemented with 1g. avizyme/ kg diet, 1000 FTU Natuophos phytase/ kg diet and a mixture (1:1:1:1) of cardamom, cumin, hot and black pepper at 2 or 4 g/kg, or a combination of avizyme and phytase, Avizyme and mixture of condiments at 2 or 4 g/kg and combination of phytase and condiments mixture at 2 and 4 g/kg and combination of Avizyme, phytase and 2 or 4 g of condiments mixture/ kg diet. Diets were iso-caloric and iso-nitrogenous. A number of 540 unsexed 7-days old Lohman broiler chicks were fed on 12 dietary treatments each contained 5 replicates of 9 chicks each. The experimental period lasted from 7 to 49 d. of age. Growth performance, carcass characteristics, chemical composition of the excrement, digestibility of nutrients and biochemical constituents of blood plasma were studied. The results obtained showed that, diet supplementation with a combination of Avizyme, phytase and 2 g/kg of condiments significantly increased the gain of body weight during the first growth period (7-21 days of age). The average live body weight gain increased significantly on using phytase supplementation alone by 7.6% compared to the un-supplemented control for the whole experimental period. Chicks fed diets supplemented with Avizyme without or with either low or high level of condiments mixture showed similar growth rate to those received the un-supplemented diet. There was no significant effect of adding neither tested enzymes and condiments mixture nor their combination on feed intake and feed conversion all over the experimental periods however, group fed diet supplemented with phytase alone recorded the best feed conversion and this was numerically better than that of the un-supplemented control by 3.6%. Chemical composition of the excrements or nutrient digestibility at 49 days of age showed no significant effect of using studied feed additives. However, groups feed on phytase diets showed a numerically better crude protein, fiber, ether extract and organic matter digestibility compared with those of the control. Neither tested enzymes and condiments mixture nor their combination had any significant effects on some blood constituents such as plasma total protein, its fractions, total lipids, cholesterol and liver functions as measured by AST and ALT enzymes. Accordingly, it can be recommended to use a combination of Avizyme, phytase and 2g/kg of condiment mixture in broiler diets during the first growth period, 7-21 days of age, to achieve a satisfactory performance. Also, phytase supplementation also has a pronounced effect on the biological responses associated with the performance at the rest of the growth period.