The cadmium mobilizing properties of two newly synthesized esters of meso-2,3-dimercaptosuccinic acid in mice have been examined. They are: di(2'-methoxyethyl) meso-2,3-dimercaptosuccinate ([-CH(SH)COOCH2CH2OR]2, R = CH3; MEDMS), and di(2'-ethoxyethyl) meso-2,3-dimercaptosuccinate ([-CH(SH)COOCH2CH2OR]2, R = CH2CH3; EEDMS), conveniently prepared from dimercaptosuccinate acid with 2-methoxyethanol and 2-ethoxyethanol, respectively. Mobilization studies in mice of aged in vivo cadmium deposits using five ip injections of 0.40 mmol/kg of each chelator in peanut oil clearly indicate that both compounds, MEDMS and EEDMS, are significantly superior to 2,3-dimercaptopropan-1-ol (BAL) in depleting the whole body burden of cadmium. The reductions caused by MEDMS and EEDMS were approximately 20 and 26%, respectively, whereas under similar dosage regimens BAL effected about only a 12% reduction. The esters were neither equal nor superior to BAL for the reduction of renal cadmium levels, MEDMS being the least effective. For the mobilization of hepatic cadmium deposits, both were quite promising (MEDMS, 20%; EEDMS, 34% reduction) compared to BAL (only 2% reduction). There was no accumulation of cadmium with either MEDMS or EEDMS in any of the other organs examined--spleen, testes, pancreas, and particularly the brain. These compounds enhance the fecal excretion of cadmium by a factor of 25- to 40-fold but have very little effect on the urinary excretion of this element. The present study reveals that the order of overall efficacy is EEDMS greater than MEDMS greater than BAL, considering the liver and whole body burdens of cadmium, but BAL greater than EEDMS greater than MEDMS in terms of the efficacy in reducing cadmium levels in the kidneys.