The present study was conducted to investigate the effect of hemi-castration on testicular size and semen characteristics of Iraqi local bucks. Eighteen adult bucks aged 1.5-2.5 years, weighing 36.9-43.7 kg were used. Animals were randomly divided into three groups (6 in each); groups 1 control group. Animals in groups 2 and 3 were subjected to hemi-castration in left and right testicles, respectively. Testicular circumference was measured two weeks before hemi-castration and ten weeks after. Semen samples were collected using electro-ejaculator two weeks after hemi-castration. Volume, color, mass motility, individual motility, percentage of live sperm, percentage of abnormal sperm and sperm concentration were analyzed immediately after collection. Results of the present study showed a significant (P<0.05) increase in testicular circumference after hemi-castration. Testicular circumference in left hemi-castration was higher than that in right hemi-castration. Result also showed a significant (P<0.05) increase in semen volume, mass motility individual motility and percentage of live sperm in semen of animal without any differences between left and right hemi-castrated animals comparing with control groups. The study concluded that hemi-castration leading to improve semen characteristics due to compensatory mechanism of the remaining testis.