Mercury concentrations were determined in muscle tissue of lake resident and anadromous populations of Arctic char in Greenland. Mercury in lake sediment, and in soil and humus from the surrounding area were also determined in the main localities. Fish length and dry weight were shown to be important covariables, which have to be taken into account when comparing mercury levels between populations. Variations in fat content did not contribute further to the differing mercury concentrations. Mercury concentrations in lake sediments, humus from around the lakes and resident populations of Arctic char from west Greenland and south-west Greenland were higher than for populations from east Greenland and north-west Greenland. The mercury level in anadromous populations was found to be 10-15-fold lower than that found in lake resident populations, and similar to that found in marine fish species. Methyl mercury was determined in two of the populations investigated, and constituted 72-92% of the total mercury.