The addition of molybdenum to samples and standards has been found to be an effective method of minimizing matrix interferences in the flameless atomic absorption analysis of lead, cadmium, and selenium. Use of this technique permits the analysis of selenium and lead in natural waters in concentrations as low as 1.0 μg/litre. Cadmium can be analyzed down to 0.1 μg/litre. It appears likely that the use of molybdenum for interference suppression could be extended to other metals. If so, this would greatly expand the usefulness of flameless atomic absorption for trace metals analysis.