To measure the exudative cutaneous copper (Cu) and zinc (Zn) losses in burns, 10 patients, aged 36 +/- 9 years (mean +/- s.d.) with burns covering 33 +/- 10 per cent of the total body surface area, were studied from the first postburn day (D1) until D7. All intakes and losses were analysed for Cu, Zn and nitrogen (N) content. Cutaneous losses were extracted from textiles surrounding the patients. Urinary excretions were 0.12 +/- 0.06mg/24h for Cu, 0.9 +/- 0.6mg/24h for Zn, and 14.1 +/- 4.4g/24h for N. Mean daily exudative losses through wound seepage from D1 to D7 were 4.7 +/- 2.1mg/24h for Cu, 27.1 +/- 14.4mg/24h for Zn, and 8.7 +/- 3.8g/24h for N. The cumulated mean losses over 7 days were 37mg for Cu, and 212mg for Zn, representing respectively 20-40 per cent and 5-10 per cent of normal body content. Serum Cu and Zn levels were strongly depressed. The urinary Cu/N ratios correlated with clinical improvement. We conclude that the exudative Cu and Zn losses during the first week postburn contribute significantly to the increased nutrient requirements in burns.