A fast (one and one-half hour) method to determine the amount of polyester in unbleached, bleached, or greige goods is described. Equipment and supplies required are a flat iron, C1 disperse 73, balances and a tri-stimulus colorimeter. Strictly controlled environmental conditions are recommended. The efficacy of this method, which makes use of the polyesterspecific thermosol dyeing method, is compared to the accuracy of AATCC Test Method 20A. The latter is a sulfuric acid dissolution technique. -- AATA