Dihydrostreptomycin, kanamycin and fladiomycin were administered intramuscularly or orally to pigs and calves. An attempt was made to identify these aminoglycoside antibiotics qualitatively in tissues and urine collected from the animals after slaughter. The kidney, liver and muscle were homogenized and used to determine the diameters of inhibition zones to be produced on Micrococcus luteus ATCC 9341 and Bacillus subtilis ATCC 6633 plates at pH 6.0; and 8.0. The urine was used undiluted and after diluted serially. Thin-layer chromatographic identification was carried out only on kidney and urine samples characterized by capacity to produce larger inhibition zones on the B. subtilis plate at pH 8.0 than on any other plate. Next, the ultrafiltrate obtained from each tissue homogenate or urine was spotted on two silica gel plates. One of the Plates was developed in the upper layer of chloroform-methanol-17% ammonia (2:1:1), and the other in n-propanel-pyridine-acetic acid-water (15:10:3:12). The Rf values obtained were a little higher than those with reference antibiotic solutions in some cases. It was possible, however, to distinguish the three antibiotics contained in a kidney or urine sample from one another by thin-layer chromatography with two solvents. Thus, the methods mentioned above were considered to be available for the identification of aminoglycoside residues in slaughtered animals. When the kidney is suspected to contain some aminoglycosides, it is recommended to carry out chromatography on the extract from the renal cortex for the identification of these substances.