Phytopathogenic fungi have the capacity to modify chemically a wide array of organic compounds turningthem into structurally related products. In this study, biotransformation of the substrate arylpropanoidtrans-cinnamaldehyde A achieved by the phylamentous phytopatogenic fungus Colletotrichum acutatum,is evaluated; the process is carried out in liquid media culture Czapeck-Dox. The biotransformationof the substrate A produces the metabolites cinnamyl alcohol B, 3-phenyl-1-propanol C, 3-phenyloxiranemethanolD and 1-phenyl-1,3-propanediol E. The structures of metabolic products are determinedby gas chromatography coupled with mass spectrometry (GC-MS) and nuclear magnetic resonance ofproton and carbon (1H and 13C NMR). The process is marked by the tendency of the pathogen to producehydroxylations on the substituent of the aromatic ring. Additionally, it has the capability to reduce thecarbonyl group and the double bond. In the process, several metabolic products used like raw materials for different industries are generated. A possible metabolic pathway of the biotransformation of transcinnamaldehydeby C. acutatum is also discussed.