Boron trifluoride-methanol complex has recently been used as the reagent in a highly specific fluor0metric method for measuring relative wheat germ content in the products of flour milling. Although the assay is suitable for use by skilled laboratory workers the reagent is too hazardous to be used by those with less specialised training, and a safer reagent would be desirable for these situations. An alternative method is now described using aqueous Na tetraborate solution as a replacement for the boron trifluoride-methanol. Experiments on dissected grain tissues and flour mill streams show that the borate has a similar specificity to that of the boron trifluoride-methanol and that the results of the two methods show a very high correlation. The fluorescence response varies from one sample of germ to another, but the accurate measurement of the germ content of milling products can be achieved by calibration against a pure sample of the corresponding germ.