Glyphosate containing herbicides are an alternative to paraquat and are widely used throughout the world. Despite animal studies showing a low mammalian toxicity, human fatalities are reported after suicidal ingestions of glyphosate. Among the numerous analytical methods proposed, the reference method is the HPLC Monsanto procedure which is available in very few laboratories. The Monsanto procedure consists of a pre-column derivatization with detection of the resulting chromophore by HPLC with a variable wavelength UV/VIS detector. We propose a simple and rapid method for the diagnosis and monitoring of glyphosate poisoning. This method uses an aminoacid analyzer (Beckman 6300) with the program for biological fluids. With this procedure the glyphosate and amino methyl phosphoric acid retention times are respectively 1.75 and 3.54 min. This method gives a rapid result. The time between collecting the sample and completing the result is 45 min. This method may be useful for the diagnosis and monitoring of glyphosate poisoning and is easy to perform with an apparatus usually available in every laboratory involved in aminoacid analysis.