This study was carried out to investigate the effect of long acting oxytetracyclin (OTC) on experimental brucella infection in rabbits. Eight brucellosis free rabbits, divided into two equal groups (A and B) were employed. Rabbits in group "A" were intramuscularly injected with 20 mg/Kg, B.W. of long acting OTC. After 6 hours, all the 8 rabbits were exposed to infection by Brucella abortus biotype 3 by subcutaneous in oculation of 0.1 ml of brucella suspension containing 1x10' cells of 2 days-old smooth culture. Rabbits in group "A" were reinjected with the same dose of long acting OTC after 48 and 96 hours from the first injection of long acting OTC. Sera were collected from these animals after 3 and 6 weeks post-inoculation and tested by the plate aglutination test (PAT) and complement fixation test (CFT). Brucella agglutinins
 
and complement fixins were detected only in sera of group "g" rabbits, but not in those of group "A". Bacteriological examination of sacrificed rabbits 6 weeks past-infection, yielded the same Brucella abortue strain from all rabbits of group "B", while no Brucella arganisms were recovered from all rabbits of group "A".