A rapid method for detecting deoxynivalenol (DON), also known as vomitoxin, was developed. DON was extracted from grains and other samples with acetonitrile-4% potassium chloride solution (9 + 1). Impurities that would interfere with detection were removed on a C18 silica gel reverse phase column. Water was removed from eluates on a hydrophilic matrix column. DON was detected by thin layer chromatography using an aluminum chloride solution to develop the blue response characteristic of the mycotoxin. Total time involved is approximately 30 min. The method was applicable to corn, wheat, and barley at detection levels of 1 ppm, and oats at 1.5 ppm. It is applicable to environmental samples (soil, green plants, and water) at detection levels of 0.75 ppm.