Most, if not all, Antarctic and Greenland snow and ice samples to be analyzed for toxic metals and metalloids such as Pb, Hg, Sb, Cd, Ag, Se, As, Cu and Zn become more or less contaminated by these elements on their outsides, mainly during field collection. We assess here the various procedures which have been developed to try to decontaminate the samples. They include both mechanical and rinsing techniques. It appears that it is essential, but very difficult, to establish clearly the efficiency of these procedures. This can however be done by determining the geometry of contamination of the analyzed samples and by evaluating procedural blanks carefully. Such careful evaluation has been achieved at present only for mechanical procedures and for a few metals.