Senna spectabilis (syn Cassia spectabilis) is one of the most important species within the Fabaceae family, natively found in Central and South America, as well as parts of Asia and Africa. Phytochemical investigations have shown that S. spectabilis produces over 40 chemical constituents, displaying antiproliferative, antitumoral and antifungal activities [1]. Aiming to understand the chemical and ecological interactions between this tree and Rinocladiella similis, fungus isolated from Senna spectabilis´s rhizosphere, we have devised a series of experiments in order to find out molecules of interest. This fungus was cultivated in Potato Dextrose Agar (PDB) medium for 28 days, at 25 °C, the broth was separated from the mycelium by filtration and the crude extract was obtained by extraction with EtOAc (3 x 33.33% of the broth volume each) and dried in rotatory evaporator. The crude EtOAc extracts were fractionated by column chromatography using reversed-phase silica gel (C-18) and eluted with ACN:H2O gradient affording five fractions. The fraction two was submitted to HPLC preparative and resulted in the isolation of the four known metabolites. 2-(4-hydroxyphenyl)acetic acid, methyl 2-(hydroxyimino)-3-(4-hydroxyphenyl)propanoate, 4-(2-hydroxyethyl)phenol and 4-hydroxybenzaldehyde. The structures were elucidated by use of NMR (1D and 2D) and HRMS. These substances have several biological activities reported such as antioxidant, anti-inflammatory, antifungal and antibacterial [2,3,4]. The preliminary results reinforce the potential of microorganisms as sources of bioactive natural products and corroborate the assumption of ecological interaction between the rhizosphere and its host plant. This is the first report of these metabolites for R. similis.