The study aimed to assess the growth performance, haematology, serum biochemistry, gonadal and extragonadal sperm reserves of two breeds of rabbit bucks fed dietary monosodium glutamate (MSG) at varying inclusion levels (0.00, 0.25, 0.50 and 0.75 g/kg diet). A total of 320 sexually mature New Zealand White Bucks and Dutch Belted Bucks aged 8 to 10 mo with average weight ranging from 1.34 to 1.96 kg were used for the study, which lasted 8 wk. The bucks were weighed and distributed to the four treatment diets. Each treatment was replicated 10 times with four bucks per replicate in a 2×4 factorial experiment. At the end of the feeding trial, 2 bucks per replicate were euthanised. Blood samples were collected from the jugular veins for haematological and serum analyses and their reproductive tracts were dissected. The testes and epididymides were carefully sampled, weighed and processed. The results showed that the bucks fed the diet containing 0.25 g MSG/kg had the best (P<0.05) feed conversion ratio and daily weight gain, daily sperm production and sperm production efficiency. The inclusions of up to 0.75 g MSG/kg diet did not compromise the bucks’ health status, performance and reproductive potential, irrespective of their breeds. However, optimum performance and sperm production were recorded at 0.25 g MSG/kg diet. This study suggests that dietary MSG at 0.25 g/kg in diet can significantly improve rabbit feed palatability, thereby bringing about optimum growth performance, sperm production, and efficiency without causing any physiological imbalance ino the bucks.