The bioavailability of zinc in normal and zinc deficient LACA mice was investigated using isotope zinc-65. The intestinal absorption of Zn in the zinc-deficient mice (71.913.6%) was significantly higher than that in the normal mice (38.8?6.8%). No difference on Zn distribution in the body was observed. Specific activity of zinc-65 in liver, spleen, kindey and muscle in the zinc-deficient mice was significantly higher than that in the normal mice. The retention curve of zinc-65 in mice was properly fitted into two exponential functions. The biological half-times of zinc in blood, spleen, lung, femur and muscle attached to femur in the zinc-deficient mice was slower and ration ratio in the slower clearance component in the zinc-deficient mice, was larger than that in the normal mice.