Bottle gourd, Lagenaria siceraria Stand. (Cucurbitaceae), fruit is used in folk medicines and for culinary purposes in Asia. The phenolics of bottle gourd fruit were investigated qualitatively by LC-MS(n). Twenty-two phenolic glycosides were detected and characterized on the basis of their unique fragmentation pattern in the negative ion mode tandem MS spectra. Twenty of them were extracted for the first time from this source, and twelve of them have not been reported previously in nature. It was also possible to distinguish between the individual classes of isobaric phenolic glycosides by tandem and high-resolution mass spectrometry. In this study we also discuss the mass spectrometric fragmentation mechanism of 6-(hydroxycinnamoyl)glucoses. This is the first report of the full characterization of phenolic glycosides of bottle gourd fruit by LC-MS²⁻⁴.