Objective The aim of our study was to develop a robust LC-MS/MS method for determination of MN and NMN in blood plasma.Methods A liquid chromatography -tandem mass spectrometric ( LC-MS/MS) method was used, with signal linearity, lower limits of quantitation, precision and accuracy being evaluated.The study recruited 126 healthy volunteers, and MN and NMN in blood plasma were determined.At the same time samples from 21 patients ( 17 pheochromocytoma, 4 ectopic pheochromocytoma) , a hypertension group of 108 persons, and a control group of 84 persons were analyzed. A paired T test was used to compare the MN and NMN levels between the different groups.Results The performance characteristics for the method in terms of linearity, lower limits of quantitation, precision and accuracy were verified.Significant differences were found between the concentration levels of MN and NMN in the diseased and healthy groups.Conclusion A robust and reliable LC-MS/MS method for the determination of MN and NMN in blood plasma has been developed and was shown to be suitable for clinical application.