Several studies have demonstrated the analgesic and anti-inflammatory effects of fruit and seed extracts from Pterodon emarginatus Vogel (Fabaceae). The objective of this study was to evaluate the antinociceptive activity of the hydroethanolic extract of P. emarginatus leaves in mice and characterize its chemical composition using HPLC coupled to UV-vis diode array detection and mass spectrometry with electrospray ionization. Our results showed that the doses of 500 and 1000 mg/kg produced an antinociceptive effect, as observed in the hot plate test and writhing induced by acetic acid. The chromatographic profile and spectral mass data suggest the presence of di-C-glycosylflavones (e.g., vicenin-2 and schaftoside), C,O-glycosylflavones (e.g., chrysoeriol-8-C-glucosyl-2'-0-glucuronide-6-C-arabinoside) and luteolin-7-C,O-rutinoside as the main constituents. Lower levels of oleanane-type saponins, such as soyasaponin Bb and Be, and the saponin derivatives hederagenin and aglycone B, which are typical of Fabaceae family, were also found. From this study, it is suggested that the analgesic effect observed is not due to the terpenoids previously reported from fruit and seed extracts, but could be attributed to flavones and the hederagenin derivatives that were identified as main constituents of the hydroethanolic extract from the leaves. Keywords: Pterodon emarginatus Fabaceae Antinociceptive Di-C-glycosylflavones Di-CO-giycosylflavones Soyasaponins, Introduction The genus Pterodon (Fabaceae/Leguminosae) is widely distributed over the savannahs of central and southern Brazil. Pterodon emarginatus Vogel (synonyms Pterodon pubescens Benth. and Pterodon polygaliflorus Benth.), also known as [...]