The relationship between the fatty acid (FA) status and indices of insulin secretion in young obese subjects at risk of developing insulin resistance and its complications was investigated. In 12 subjects (8-14 years) at first diagnosis of obesity the FA composition of total plasma and circulating and erythrocyte phospholipids was related to basal and peak insulinemia and the insulinemic area resulting from a standard oral glucose tolerance test. Negative correlations were shown between both delta-6-desaturation products and 20:5 n-3 levels and insulinemic values. On the contrary, circulating total saturated and monounsaturated FA and erythrocyte phospholipid products of delta-5- and delta-4-desaturation positively correlate with insulinemic indices. The observed relationships could be markers of developing insulin resistance and suggest the possibility of a dietary intervention.