Bacterial endotoxin induces gel-formation of amebocyte lysate. This gelation test, the limulus test, was first described by Levin and Bang [1]. The limulus test has been widely used for the detection of endotoxin, not only in fundamental bacteriological research but also in clinical diseases [2]. Although the technique of the limulus test is simple, the endotoxin level can not be determined quantitatively. We developed a method to determine the endotoxin in physiological saline solution and glucose solutions using a fluorescent probe, fluorescamine.