Geese have a short reproductive live and ganders produce low quality semen under Egyptian heat stress condition. This study aimed to evaluate the effect of dietary L-arginine (AR) supplementation on semen production, testosterone level, and testes histological structure of Egyptian geese. Total of 30 males of Local Egyptian geese (10 months of age and 3.20±0.25 kg BW) were divided into three groups (10 in each). Ganders in the first group (control, G1) were fed ad libitum on a commercial mash feed (15.2% CP and ME of 2690 Kcal/kg) while those in G2 and G3 were fed the control diet with 0.2 and 0.4 g AR/kg, respectively. Treatment lasted for two months as a feeding period and then semen was collected for five weeks. Results showed that all semen characteristics (motility, livability, abnormality, and concentration) and total, motile, live, and normal sperm outputs/ejaculate were improved by AR-diets compared with control. The pathological score of testicular lesions were decreased by increasing AR level. Seminiferous tubule (ST) diameters (smallest, largest and mean) were increased in both AR groups compared with control. Gander testes in G3 displayed regular arrangement of spermatogenic cell layer in ST including spermatogenic cells at gradual levels of development and large lumen of ST. Plasma testosterone level increased in G3 and G2 than in G1, respectively.Dietary supplementation of L-arginine may be used as beneficial tool for improving production and quality of semen in Egyptian male geese under heat stress conditions.