The interaction between Vitis vinifera and trunk disease fungi requires better understanding. We studied the role of phenolics as possible plant defense compounds in this context. The impact of 24 grapevine phenolic compounds was determined on 6 major wood decay fungi by an in vitro agar plate assay. Hydroxystilbenoids, especially oligomers such as miyabenol C, isohopeaphenol and vitisin A and B, greatly reduced the growth of the fungi, except that of Phaeoacremonium aleophilum. A detailed investigation in 10 Botrysophaeriaceae strains revealed that all the studied members of this family display a common susceptibility to phenolics that is more or less significant. Then we undertook a quantitative analysis of stilbenoid content in grapevine plantlets inoculated with Botryosphaeriaceae to investigate whether in planta these fungi have to counteract the most active phenolics, such as hydroxystilbenoids. Based on our results, the possible role of phenolics in grapevine defense against trunk disease agents is discussed.