Five rams aged 4 years were used in this study. Semen was collected weekly from each ram for successively 4 weeks as control, then Ivermectin was injected S/C with therapeutic dose (0.2 mg/kg body weight). After one week from injection semen samples were collected from each ram once weekly for 10 weeks. Semen was evaluated for volume, sperm cell concentration, percentage of individual motility, percentage of live spermatozoa and percentage of abnormal spermatozoa. Testicular circumference, reaction time and body temperature were recorded. In addition any signs of inflammation were observed. The obtained results showed that semen volume increased significantly in the 1s and the 2nd period of Ivermectin injection (1.47+0.1 VS 2.43Ł0.21 and 2.25 +0.12 ml) after that it reduced nearly to normal level before treatment (1.17+0.14ml). The same trend was observed on sperm concentration where the increase began at the 1% period of treatment till the end of the 2 one (3467+218.6 VS 3610+663.95 and 3705.3+195.4x10/ml) then reduced at the 3rd period of treatment (3288–309.4x10°/ml). Also, the percentage of abnormal spermatozoa increased significantly (P<0.01) specially coiled tail all over the periods of treatment (1.85+0.26 VS 6.73+0.88, 8.93 1.48 and 4.85 +0.86 %). While, the percentage of live spermatozoa reduced significantly (P<0.01) through the periods of treatment (87.75+1.71 VS 82.33=1.85, 80.60 +2.97 and 80.5 +1.72 %). The testicular circumference increased significantly (P<0.01) till the end of the 2nd period of treatment then declined in the 3rd one (31.35+ 0.49 VS 33.2=0.57, 33.15+0.57 and 32.3+0.57 cm. respectively). On the other hand, Ivermectin treatment doesn't revealed any significant effect on percentage of individual motility, reaction time and the body temperature. On the same line, rams differ significantly (P<0.01) in their response to ivermectin on semen volume, sperm concentration and testicular circumference. Furthermore, interaction between periods of treatment and ram individual variation was pronounced significantly in sperm concentration and rise in body temperature. Also, local inflammation developed during the 1st period of treatment on the perineal as well as perpetual regions in all tested rams and disappear after the end of the 2nd period of treatment. So, Ivermectin can be used safely as antiparasitic drug for sheep but during the treatment period rams can be used for breeding under restricted observations.