Abstract: A single rapid procedure for the quantitative and qualitative analysis of flavonoid glycosides and steroidal glycosides, in natural products, has been developed. The material is extracted with aqueous solutions of polar organic solvents in an ultrasonic bath. Interfering compounds are removed by pre-purification procedures prior to instrumental analysis by High Pressure Liquid Chromatography with Negative Ion Electrospray Mass Spectrometric Detection and on-line Diode Array Ultraviolet-Visible Spectroscopy. The analysis of flavonoid and steroidal glycosidic compounds in HOSTA leaves served as a model system.