The procedure of Garrison and Freedman will be used to induce bacterial endocarditis in rabbits. Both right-sided and left-sided endocarditis will be studied. Problems to be emphasized are: role of intravenous narcotic use, etiologic agents (Pseudomonas, Streptococcus fecalis, Bacteriodes, Aspergillus), antibiotic synergism, duration of therapy, prophylaxis, new antimicrobiols (Amikacin, Tobramycin, Cefazolin), renal failure, mycotic aneurysm formation, and immunological consequences.