The concentration of mercury in 178 blood samples and 32 hair samples from the Angmagssalik district in East Greenland has been determined. For Greenlanders mercury concentrations are highly dependent on the amount of seal eaten. In the most heavily exposed group (eating more than six meals of seal per week), a significant positive correlation between blood mercury and age was demonstrated. No differences according to sex were demonstrated when the mean values were corrected for influence of age. In the most heavily exposed group, a mean value of 62.5 micrograms Hg/l was found, while in the group eating 1 meal of seal or less per week, the mean value was 22.2 micrograms Hg/l. In the control group consisting of Danes living temporarily in the district, the mean blood mercury concentration was 5.8 corresponding to the fact that they eat seal only occasionally. Hair mercury concentrations were found to correlate well with blood mercury concentrations (r=0.9222). The hair/blood ratio was estimated to 289. It is concluded that the present relatively high mercury exposure in Greenland does not exert any immediate risk of intoxication to the adult population, but supplementary investigation on fetal exposure is needed.