BACKGROUND: Nowadays, Coenzyme Q10 is used in male infertility treatment as an oral or injectable supplement. The main role of coenzyme Q10 is presence in the electron transport chain during cellular respiration process to produce energy in the mitochondrial membrane. OBJECTIVES: The purpose of the current study was to evaluate the effects of Coenzyme Q10 on morphological characteristics of the testis and histological features of seminiferous tubules in ostrich. METHODS: 18 male ostriches, 6 months old, from South African breed (struthio camelus australis) were selected and divided into three groups of 6. Group one (control) was fed only by maintenance ration. The second group received 10 mg/kg and the third one, 20mg/kg of Coenzyme Q10 in their food. Coenzyme was given orally and once daily. After two months, the birds were slaughtered and gonadosomatic index (GSI), weight, height and diagonal of testis, diameter of the seminiferous tubules as well as lumen diameter, the height of their epithelium and also the number of spermatogonial cells, primary spermatocyte, Sertoli and Leydig cells were compared in the control and experimental groups. At the beginning and on 30th and 60th days of the experiment, blood samples were taken from the birds for endocrinology investigations and the plasma was separated for measuring the plasma concentration of testosterone and cholesterol. RESULTS: After feeding ostriches with Coenzyme Q10, weight, height, diagonal and testicular gonadosomatic index increased significantly in the experimental groups compared to control group (p|||£0.05). The histometric surveys also showed a significant increase of seminiferous tubules diameter, lumen diameter, height of epithelium and there was also a significant increase in the number of spermatogonial cells, primary spermatocytes, sertoli and leidig cells (p£0.05). The endocrinology evaluations revealed the increase of plasma concentration of testosterone in treatment groups in comparison to the control group; however this increase was not significant for cholesterol level. CONCLUSIONS: Oral Coenzyme Q10 may have favorable effects on reproductive characteristic of the male ostriches.