Muellera, Dahlstedtia and Lonchocarpus genera (Fabaceae) are very similar in terms of taxonomy as well as secondary metabolites biosyhtnesis.1 In a recent study it was investigated the relationships of Lonchocarpus and allied genera based on nuclear and plastid DNA markers. Some species from section Laxiflori of Lonchocarpus, Bergeronia and Margaritolobium were transferred to Muellera.2 This genus comprises 26 species, of which 10 are new, among them Muellera graciliflora.3 In this context, this study aimed a phytochemical investigation from extracts of the roots of M. graciliflora. Dried roots bark of M. graciliflora were powdered and successively extracted at room temperature with petroleum ether (PE), ethyl acetate (EtOAc) and methanol (MeOH). The PE and EtOAc extracts were submitted to flash column chromatography and successive preparative thin layer chromatography. Their structures were established by NMR (1D and 2D) data, and comparison with literature data. The crude extracts of leaves and roots were subjected to antiproliferative activity in vitro, being the PE extract of the roots the most active. The study from M. graciliflora furnished five substances in the EtOAc extract (one dibenzoylmethane, and four flavones) and five in PE extract (four dibenzoylmethanes, and one flavanone). The 1H NMR spectrum of the dibenzoylmethanes is very similar, showing a hydroxyl group characterized by the singlet at δ 16.90 ppm (s, 1H, 7 or 9-OH) attributed to an internal hydrogen bond to a carbonyl. This type of structure was in accordance with the equilibrium keto – enol of the dibenzoylmethane skeleton. Others dibenzoylmethanes derivatives showed the presence of the dimethylalyl substituent at C-8 (δ 6,09 ppm (1H; dd; J = 17,4 e 10,8 Hz, H-2’’’), δ 4,92 ppm (1H; dd; J = 17,4 e 1,0 Hz, H-3a’’’) and δ 4,89 ppm (1H; dd; J = 10,8 e 1,0 Hz, H-3b’’’) and two carbonyl groups in the 13C NMR spectrum. These data were in agreement with a non-enolizable dibenzoylmethane skeleton. The five identified dibenzoylmethanes are unpublished in the literature. The flavanone was isolated of Lonchocarpus montanus and the identified flavones in species of Lonchocarpus and Dahlstedtia. This study is the first phytochemical study of the Muellera graciliflora species. Five compounds are being described for the first time in the literature and in the genus Muellera. Prenylated flavonoids containing furan, 2",2"-dimethylpyrano and dimethylalyl substituent has been considered as markers these genera in the Fabaceae family.