Australian Aborigines develop a high frequency of type-2 diabetes mellitus when they make the transition from a traditional to an urban life-style. Preliminary studies were conducted at an outstation in northeastern Arnhem Land where the Aborigines have been exposed to Western influence for approximately 20 years only and where they continue to follow a life-style that is largely traditional. At the time of the study 31 persons were resident at the outstation, 20 persons were over 15 years of age (adults) and 11 persons were under 15 years of age (children). Eighteen adults and six children were tested. By standard criteria for body mass index these persons were all underweight (less than 20 kg/m2). In spite of this, they displayed no biochemical evidence of malnutrition. Their plasma fatty-acid profiles were consistent with a low dietary fat intake and a high consumption of lean meat. Levels of linoleic acid were much lower and those of arachidonic acid were much higher than are those in persons who consume a Western diet. Fasting glucose and cholesterol concentrations were low relative to those of urbanized Aborigines and white Australians. However, their fasting insulin and triglyceride levels were inappropriately high for their very low body mass index and fasting glucose levels. The mild elevation of triglyceride and fasting insulin levels is consistent with insulin resistance and suggests that these Aborigines (in common with other Aborigines) may become susceptible to obesity and diabetes if they became urbanized further.