The aim of this study was to investigate the effects of poor and rich rations on carcass characteristics in sheep actively immunized against LHRH using ovalbumin-LHRH-7 fusion protein. Thirty ram lambs at 19 weeks of age were used in 1 (immunized, n = 10), E (castrated with elastrator, n = 10) and C groups (intact, n = 10). Animals in 1 group were immunized against LHRH using ovalbumin-LHRH-7 (OL) protein generated by recombinant DNA technology as a primary and a booster injection at 19th and 23rd weeks of age respectively. Each group was divided into 2 subgroups (11, n = 5; 12, n = 5; El, n = 5 and E2, n = 5; Cl, n = 5; C2, n = 5) in the 31st week of the birth. Animals were housed in groups and fed with their rations for 6 weeks. The animals in the Cl, 11 and El groups were fed with low protein and energy ration (RI; 11.3% CP, 2290 Kcal kg(-1) ME), whereas in the groups C2, 12 and E2 were fed with high protein and energy ration (RII; 16.2% CP, 2438 Kcal kg(-1) ME). Rations were enriched with vitamins and minerals. At the end of the feeding period, all animals 41 weeks old were slaughtered. The results showed that testis weights and rates of the C groups were different from 1 end E groups both in RI and RII (p<0.05). However, castration with immunization or elastrator reduced testis weight. Lamb chop, internal fat, testis, back-lion, forearm, shoulder and neck weights in C group in RI were different from those in I and E groups (p<0.05). Forearm in C; lamb chop in 1, E and C; bone weights in I were different between RI and RII treatments (p<0.05). Neck in I, E and C; internal fat rates in I, E and C were different in RI (p<0.05). Kidney and pelvic fat in 1, E and C; neck in I, E and C; internal fat rates were different in RII (p<0.05). Pre-slaughtered live weights; warm and cold carcass weights; dressing percentage of the C group appeared to be higher than other groups in RI and RII, but these differences were not significant.