The genus Virgaria was first proposed in 1817 1 and classified in the family Xylariaceae. 2 Virgaria nigra, a type species of Virgaria, is a commonly encountered hyphomycetes and has been illustrated in numerous publications. [3][4][5] However, little work has been done on the chemical constituents of Virgaria species, and only one compound, vinigrol, has previously been isolated from V. nigra. 6 As part of our interest in the presence of novel metabolites in Virgaria sp., we investigated the chemical constituents of a culture broth of a newly discovered Virgaria sp. FKI-4860 that resulted in the isolation of a new compound, virgaricin (1). This compound was found to be an analog of pramanicins and TMC-260. [7][8][9] In this study, we describe the isolation, structure elucidation and antimicrobial activity of 1.Fungal strain FKI-4860 was isolated from a soil sample collected in the Bonin Islands, Tokyo, Japan. It is characterized by olive gray colonies, and solitary, mainly reniform and light brown sympodial conidia. The rDNA internal transcribed spacer (ITS) sequence of strain FKI-4860 was elucidated and deposited at the DNA Data Bank of Japan, with the accession number AB670709. With respect to sequence distances elucidated by the MegAlign programs from the Lasergene 9 package (DNAStar Inc., Madison, WI, USA), FKI-4860 had 90% similarity with the ITS sequences of V. nigra CBS 525.69 (AB670712). From the results of morphological characteristics and sequence analysis, strain FKI-4860 was identified as a novel species of Virgaria. 10 Strain FKI-4860 was grown and maintained on a LcA slant consisting of 0.1% glycerol, 0.08% KH 2 PO 4 , 0.02% K 2 HPO 4 , 0.02% MgSO 4 Á7H 2 O, 0.02% KCl, 0.2% NaNO 3 , 0.02% yeast extract and 1.5% agar (adjusted to pH 6.0 before sterilization). A loop of spores of Virgaria sp. FKI-4860 was inoculated into 10 ml of seed medium, which consisted of 2.0% glucose, 0.2% yeast extract, 0.5% Polypepton (Wako Pure Chemical Industries, Osaka, Japan), 0.05% MgSO 4 Á7H 2 O, 0.1% KH 2 PO 4 and 0.1% agar (adjusted to pH 6.0 before sterilization), in a test tube. The inoculated tube was incubated on a rotary shaker (300 r.p.m.) at 27 1C for 3 days.