This research was carried out to study the effect of dietary garlic extract on some blood, immunity and growth parameters in common carp fingerlings. One hundred thirty five fish with an average weight of 15 ± 3.4 g were cultivated in 9 aquariums of 20 liters, with a density of 15 in each. Fish were fed with two diets of 1 and 5 g kg^-1 garlic extract for 8 weeks. By the end of the eighth week; growth, blood and immunity parameters were measured in fish. Mean temperature, dissolved oxygen and pH during the experiments were 17.01 ± 1.7 °C, 7.23 ± 0.41 mg L^-1 and 7.51 ± 0.81, respectively. Fish were fed with 5 g kg^-1 garlic extract had lower FCR (Feed Conversion Ratio) than the control group (p<0.05). Final weight, weight rate, Specific Growth Rate (SGR), and mean daily growth in treatment groups did not show a significant difference with the control group (p>0.05). The highest number of White Blood Cells (WBC), Lymphocyte, the highest amount of Lysozyme and IgM were reported in fish receiving the 5 g kg^-1 garlic extract compared to the control (p<0.05). Based on the results, garlic extract at 5 g kg^-1 supplemented diet can improve some parameters of the blood, immune and growth of Common Carp fingerlings.