A trial was carried out to investigate the effect of drinking water supplemented with dry powder Spirulina algae extract (SP) on productive performance and immune response of growing Japanese quail. A total of 480, 1-d-old quail chicks were randomly assigned equally to 4 treatments for 5 wks. The 1st treatment served as a control, fed a basal diet and drinking water with no supplement, while, the 2nd, 3rd and 4th treatments fed the basal diet and drinking water supplemented with SP extract at a rate of 0.5, 1 and 2 g /Liter, respectively. The results indicated that there was significant improvement of SP extract supplementation on the average body weight gain, health, viability with highest decrease in chicks mortality percent of all supplemented groups. Moreover, the lowest feed consumption and feed intake beside the best significant feed conversion ratio, feed efficiency and European Production Efficiency values were observed in all treated groups. Results also revealed significant (P≤0.05) increase in the relative weights of carcass, liver, heart, lymphoid organs, sex organs, proventriculus, ventriculs, and small intestine length. Abdominal fat was significantly decreased following increasing levels of SP. Moreover, the hematological responses and serum antibody production against Newcastle virus, plasma total protein profile, total antioxidant capacity and Thyroxin (T₄) concentration were significantly (P≤0.05) increased in all treated groups. However, plasma cholesterol and total lipids had marked lower levels in all supplemented groups. Plasma ALP, ALT and AST activities are fell within the normal range among groups. Therefore, supplementing SP algae extract may possibly maximize the physiological, productive performance and immune response of growing quail chicks.