The study aimed to evaluate the effects of metabolizable energy levels in the diet on rabbit semen characteristics in Mekong Delta conditions (Temperature Humidity Index (THI) 28.2±0.50). Thirty-five crossbred bucks (New Zealand White x local), with an average weight of 2.38 ± 0.16 kg, were used in a completely randomized design consisted of five treatments and seven replications, with one buck as an experimental unit. The five experimental treatments were diets containing 9.5, 10.0, 10.5, 11.0, and 11.5 MJ/kgDM metabolizable energy corresponding to ME9.5, ME10, ME10.5, ME11, and ME11.5, respectively. The experiment was carried out for 18 weeks in which the sperm of bucks was collected by an artificial vagina and analyzed weekly from the sixth week until the eighteenth week. The results showed that there was no difference (P>0.05) in terms of the final live weight, daily weight gain, and testosterone concentration. However, the testicular measurement results (testis length, testis weight, and testis volume) were significantly different (P