A Dynamic Reaction Cell(TM) inductively coupled plasma mass spectrometer (DRC-ICP-MS) was evaluated for the determination of arsenic, lead, cadmium, mercury, and thallium in urine and whole blood. Reaction cell conditions were evaluated for suppression of ArCl + and CaCl + polyatomic interferences. The reaction gas was 5% hydrogen in argon. Lead, cadmium, mercury, and thallium were determined with the reaction cell vented. Mixture of 2.5% t-butanol, 0.5% HCl, and 2 mg Au/l plus Ga, Rh, and Bi internal standards was used to dilute whole blood and urine. Calibration was achieved using aqueous acidic standards spiked into urine matrix. Urine and whole blood addition calibration curves were nearly identical for all five elements. DRC-ICP-MS detection limits were equivalent or better than conventional ICP-MS. Within run coefficients of variation (CV's) were nearly the same for DRC-ICP-MS and conventional ICP-MS for National Institute of Standards and Technology (NIST) SRM 2670 and BioRad Lyphochek Urine Metals Control. DRC-ICP-MS within run CV's for As, Pb, Cd, and Hg were 1.9%, 4%, 1.7%, and 1.7%, respectively, for NIST 2670 and 2.9%, 1.8%, 3.4%, 1.7%, and 1.0% for BioRad urine. BioRad Lyphochek Whole Blood control concentrations and CV's were: 78 μg/l (3.8%), 284 μg/l (0.52%), and 544 μg/l (0.9%). With the exception of mercury day-to-day CV's for certified whole blood and urine controls were less than 4% on both the DRC-ICP-MS and conventional ICP-MS.