A method for quantitative extraction of extravasated dye from the skin was studied in guinea pigs and rats. A simple method with a low cost and good recovery was established as follows; A piece of the skin containing extravasated dye was soaked overnight in a stoppered glass tube containing 1 ml of 1 N KOH at 37 C. Then, 9 ml of mixed solution of 0.6 N H3PO4 and acetone (5:13) was added to the tube. The tube was shaken vigorously for a few seconds and centrifuged at 3,000 rpm for 15 min. Absorbance of supernatant was measured at 620 nm. The recovery rate of the dye was about 95 per cent both in guinea pigs and rats. Using this method we observed that fasting stress significantly reduced the intensity of skin reaction induced by chemical mediators, heterologous PCA and especially homologous PCA in guinea pigs.