A total of 480 day old embryonated eggs were equally divided into four groups and treated with in-ovo inoculation of L-arginine as 1, 2, 3% and compared with control. Each group contained 120 eggs. G-1^st was injected with 1% arginine solution (1gm/100ml distilled water). G-2^nd was injected with 2% arginine solution (2gm/100ml distilled water). G-3^rd was injected with 3% arginine (3gm/100ml distilled water). G-4^th was control group. Four birds per replicate (n=5) were selected for slaughtering and collection of samples done for histo-morphometry and meat parameters analysis. The results of histo-morphometry of thigh muscles have indicated the growth of muscles. Drip loss, cooking loss of muscles have indicated the water holding capacity of tissues while lightness and yellowness of meat expressed the meat quality characteristics like tenderness, colour and juiciness of meat. Hence, it was concluded that the addition of L-arginine has significant beneficial effects on the growth performance of birds, histo-morphometry of thigh muscles and improved the meat quality on injecting 3% L-arginine compared to 2%, 1% and control groups.