Carob belongs to the Fabaceae family, which has been studied for its medicinal properties, showcasing an-tioxidative properties and the ability to enhance sexual and immune system functions. This study aimed at examining the effect of adding hydro-alcoholic extracts of carob seeds to the diet on steroid hormones, sperm parameters and blood parameters of Lori-Bakhtiari rams. In this study, carob seeds were extracted using the percolation method. Thirty Lori-Bakhtiari rams were selected with a mean weight of 50 ± 5 kg and mean age of 2.5 years old. They were equally divided into three groups: (1) control (without carob ex-tract), treatment (1) 150 mg/kg body weight (BW), and treatment (2) 300 mg/kg of carob seed extract in the diet for 4 weeks (2021-2022) for adaption process. Then semen and blood were analyzed for four months. Sperm motility, viability and the hypo-osmotic swelling (HOS) tests were evaluated at pre-freezing and post-thawing by the Computer Assisted Semen Analysis (CASA) software, Eosin-Nigrosin staining and a phase-contrast microscope, respectively. Furthermore, blood samples were collected for evaluation of fast-ing blood sugar (FBS), cholesterol (CH) and triglyceride (TG), serum creatinine (sCr), high-density lipopro-tein (HDL), low-density lipoprotein (LDL), and testosterone hormone (T). The results of this study showed that the sperm parameters like motility and viability in the treatment groups increased significantly (P<0.05) in pre-freezing and post-thawing evaluations. Additionally, the results of blood parameters showed that FBS, CH, TG, LDL and sCr were significantly decreased by using the carob extract in a diet (P<0.05), while the testosterone level significantly increased during the experiment (P<0.05). In conclusion, the use of 300 mg/kg carob extract in the diet showed a more positive effect on sperm and blood parameters at Lori-Bakhtiari rams. تفاصيل المقالة