X-ray fluorescence was adapted to the analysis of 22 terricolous lichen species from 14 sites in the Mackenzie Valley, Northwest Territories, and 7 species from the Sudbury District of Northern Ontario. X-ray fluorescence (XRF) proved to be faster and exhibited better sensitivity and reproducibility than conventional analytical techniques; also, the samples were not destroyed in the analysis. Procedural details of the XRF method are given. The levels of copper, iron, nickel, and sulphur in Arctic lichens were similar to those found in lichens growing on the periphery of the Sudbury pollution zone but very much lower than in specimens nearer the nickel smelter. A linear relationship between concentration and the reciprocal of the distance from the Copper Cliff smelter was confirmed for the occurrence of these four elements in samples collected along a 60-mi NNW transect.