Levels of mercury, methylmercuri and selenium were determined in liver samples from wild mink (Mustela vision) caught in the Norwegian countries of Rogaland (38 samples), Sogn og Fjordane (15 samples) and Hedmark (18 samples). The average mercury levels from these counties were 2.6, 3.1 and 2.1 micrograms Hg/g wet weight, respectively. No significant differences in mercury levels were found. The methyl mercury levels (MeHg) were determined in 30 samples. A very strong positive correlation between total mercury (Hg) and methyl mercury (r = 0.91, P less than 0.001) was found. The average methyl mercury level was 35 per cent of total mercury. This indicates that wild mink has the ability to demethylate mercury. The selenium levels were determined in 35 samples. A strong positive correlation between the levels of total mercury and selenium (r = 0.87, P less than 0.001) was found. There was no correlation between age or nutritional condition and mercury level. In the present study mink was examined to see of it could be recommended as an indicator species for monitoring the local environment for mercury contamination. No definite answer to this question could be found. The study did reveal, however, that in all the counties studied there are individuals that are considerably contaminated with mercury.