Oenanthotoxin as crude yellow crystals was obtained, after the extraction and treatment from Oenanthe crocata L. fresh roots. The fluorescence response of oenanthotoxin solutions undergo changes, depending on the solvent used. Chloroformic solutions of oenanthotoxin showed a maximum fluorescent emission at 425 nm when the exciting wavelength was at 370 nm; in methanol it was displaced (lambda ex 375 nm, lambda em 435 nm), and in benzene showed a lambda em at 450 nm when the lambda ex was 395 nm. There was a linear relationship shown between the oenantotoxin concentration and fluorimetric response while within suitable experimental limits, the minimum concentration detected was 9.02 micrograms/ml. Using these properties, a fluorimetric method has been developed for the identifications and evaluation of oenanthotoxin.