It is shown that o-carboxyphenylglyoxal, which is converted from ninhydrin by alkali, produces a chemiluminescent lucigenin reaction under alkaline conditions when with reacted with guanidino compounds. It is also demonstrated that phenylglyoxal, which is a model compound of o-carboxyphenylglyoxal, produces a strong chemiluminescent lucigenin reaction under alkaline conditions when reacted with guanidino compounds. Moreover, ESR spectra showed the presence of 5,5-dimethyl-1-pyrroline N-oxide (DMPO)-spin adducts of superoxide anions in a mixture of phenylglyoxal and guanidino compounds under alkaline conditions. It was confirmed that the superoxide anions were generated by the reaction of phenylglyoxal with guanidino compounds under alkaline conditions, thereby causing lucigenin chemiluminescence. The chemiluminescent reaction of lucigenin in a mixture of phenylglyoxal and the guanidino compounds was applied to HPLC for guanidino compounds. The present chemiluminescence-HPLC system has a 2-fold greater sensitivity than chemiluminescence-HPLC using ninhydrin. Arginine, guanidine and methylguanidine were detected in serum from a hemodialysis patient with chronic renal failure.