A continuous-flow microwave-assisted digestion technique was tested with a view to the evaluation of its effectiveness for decomposition of environmental samples. A CEM SpectroPrep system was used at moderate powers and pressures of up to 2413 kPa to perform on-line digestion of slurried samples of biological tissues (0.5% m/v) and marine sediment (1% m/v). The efficiency of oxidation of biological matrices, as characterized by the residual carbon content of the solutions, was 64%. Recovery of trace elements averaged 90±1% and was accommodated with the use of suitable internal standards. Accuracy was verified by analysis of certified reference materials from the National Research Council of Canada, marine sediment BCSS-1 and lobster hepatopancreas tissue LUTS-1. Precision of measurement, as reflected in the determination of the trace metal content in replicate solutions, using a variety of atomic spectrometric techniques, was better than 1% RSD (relative standard deviation).