The relative proportions of the five major fatty acids present in the epidermal polar lipids isolated by swabbing the surface of the skin over hypertrophic scars were compared with the relative proportions observed in normal skin. This comparison necessitates taking the 'normal' sample from unburned skin in an anatomically equivalent area on the patient investigated. When pairs of samples obtained at random from 25 patients attending a pressure therapy clinic with scars of widely differing maturity were analysed, 16 of the 27 sample pairs showed lower levels of essential fatty acid (linoleic acid, C18:2) in phospholipids from over the scarred area compared with the 'area-matched' control normal sample. There did not appear to be any scar-age-related variation in essential fatty acid content. The results suggest that the pathogenesis of hypertrophic scar formation does not necessarily involve a simple overall deficiency of linoleate but that there are considerable differences in the lipid content of epidermis over hypertrophic scars and that of normal skin.