Background: Infants at risk of atopic dermatitis have lower than normal levels of long chain polyunsaturated fatty acids. These fatty acids are normally present in substantial quantities in human breast milk. Methods: Because of the equivocal evidence concerning the ability of breastfeeting to delay the onset or reduce the severity of atopic dermatitis, we have analyzed the fatty acid composition of breast milk from the mothers of children with newly developed disease with the use of gas chromatography. Results: Breast milk lipids from mothers of children with newly developed atopic dermatitis had increased proportions of linoleic acid and significantly decreased proportions of its long chain polyunsaturated derivatives compared with a control group. The ratio of linoleic acid to the sum of its metabolites, gamma-linolenic acid, dihomo-gamma-linolenic acid, and arachidonic acid was 11.78 in the atopic group and 9.02 in the control group (p < 0.01). Conclusions: These results are consistent with previous findings of an abnormal fatty acid status in atopic subjects and may account for some of the inconsistent results from studies of the effect of breastfeeding on the subsequent development of atopic dermatitis. We conclude that further studies to examine the effects of supplementation of the diet of breastfeeding mothers with long chain polyunsaturates should be done.