A method for determining210Po in marine samples by wet dissolution, deposition onto silver disc and counting by -spectrometry is described. Recovery of polonium was obtained with208Po tracer.210Po levels in fish from the Brazilian coast and sediments from Antarctic region were determined. Levels in fish ranged from 0.5 to 5.3 Bq·kg–1 wet and for sediments, mean values of 10 mBq·kg–1 were obtained.