As part of the examination of emergency-slaughtered animals for the presence of antibiotic residues, studies were done to see whether false-positive results would be obtained when the Sarcina lutea kidney test and Bacillus subtilis BGA test were performed. When the S. lutea kidney test was positive in cattle, calves and swine, penicillin was invariably found to be present in those animals, the histories of which showed that they had not been given antibiotics. A syringe and an injected fluid containing penicillin residues are regarded as possible causes of these positive results. When the S. lutea kidney test was performed in horses which had been in a state of stress prior to slaughter, false-positive results were occasionally observed. When the German B. subtilis BGA test was used, a large number of false-positive results were recorded, among others in equine kidneys. This shows that the use of this test in examining the kidney is a highly controversial matter. A number of drugs used in veterinary medicine may have an inhibitory effect on the growth of S. lutea and B. subtilis BGA test organisms in vitro. When these drugs were used therapeutically (in vivo), the result of the S. lutea kidney test was not positive in any of the cases studied. On the other hand, false-positive results were obtained when the B. subtilis BGA renal medullary test was performed in those animals in which lidocaine and calcium borogluconate had also been injected.