AIM: To investigate the tissue distribution, urinary and fecal excretions of 125I-lidamycin (125I-C-1027) in mice and its biliary excretion in rats.METHODS: The total radioactivity assay (RA method) and the radioactivity assay after precipitation with 200 mL/L trichloroacetic acid (TCA-RA method) were used to dete-rmine the tissue distribution, and the urinary and fecal excretions of 125I-C-1027 in mice and its biliary excretion in rats.RESULTS: Tissue concentrations reached the peak at the fifth minute after administration of 125I-C-1027 to mice. The highest concentration was in kidney, and the lowest in brain at all test-time points. The organs of the concentrations of 125I-C-1027 from high to low were kidney, lung, liver, stomach, spleen, uterus, ovary, intestine, muscle, heart, testis, fat, and brain in mice. The accumulative excretionamounts of 0-24 h, and 0-96 h after administration of125I-C-1027 were 68.36 and 71.64% in urine, and 2.60 and 3.21% in feces of mice, respectively, and the accumulative excretion amount of 0-24 h was 3.57% in bile in rats.CONCLUSION: Our results reflect the characteristics of the tissue distribution, urinary and fecal excretions of 125IC-1027 in mice and the biliary excretion of 125I-C-1027and its metabolites in rats, and indicate that 125I-C-1027and its metabolites are mainly distributed in kidney, and excreted in urine.