Gas-liquid chromatography analyses have been carried out to investigate the composition of esterified fatty acids in the plasma lipids in 130 Greenland Eskimos, compared with those of 32 Greenland Eskimos living in Denmark and of 31 Caucasian Danes in Denmark. While the Eskimos living in Denmark did not differ substantially from other persons living in Denmark and, from what is found in other studies in Western communities, the Greenland Eskimos showed a completely different pattern. They demonstrated a much higher proportion of palmitic, palmitoleic, and timnodonic acids, while they had a markedly lower concentration of linoleic acid. The total concentration of polyunsaturated fatty acids was lower in Greenland Eskimos than in the other groups. These findings are discussed in the light of the generally accepted opinion of the beneficial effect on plasma lipid levels and on the morbidity of coronary atherosclerosis of a high dietary intake of polyunsaturated fatty acids. As plasma lipid and lipoprotein levels in Greenland Eskimos in a previous study were found markedly lower than those found in Western populations, and as coronary atherosclerosis seems to occur far less commonly among Eskimos in Greenland than among peoples in industrialized countries, it was found difficult to combine these observations with the results from the present study. If dietary differences are the main reason for the differences in plasma lipid concentrations, the results from the present study point more toward qualitative than toward quantitative differences in respect of fatty acid composition of the food.