The cadmium resistance of Lactobacillus and its mechanism were examined, with the following results: (1) The 16 strains of Lactobacillus were classified into two groups: 6 strains which were sensitive to cadmium and 10 strains which were resistant to more than 1mM cadmium. (2) All cadmium sensitive strains belonged to L. plantarum and L. fermentum species, and all cadmium resistant strains were L. casei and L. acidophilus species. (3) The barrier to cadmium influx in cadmium resistant strains showed no difference between L. casei and L. acidophilus strains. (4) The cytoplasmic cadmium contents in L. casei were higher than those in L. acidophilus, and there was a significant difference between L. casei and L. acidophilus (P<0.01). (5) From these results, L. casei appears to possess a mechanism for the detoxication of cytoplasmic cadmium using cadmium binding proteins and L. acidophilus appears to have a mechanism for pumping out cytoplasmic cadmium.