The title compound, C(13)H(12)Cl(2)O(5), is an isocoumarin compound which has been isolated from the ethyl acetate extract of the fermentation broth of actinomycete Streptomyces sp. (V(4)) from the South China Sea. There are intra- and inter-molecular hydrogen bonds and halogen bonds [Cl⋯Cl = 3.434 (2) Å; C-Cl⋯Cl = 121.6°]. The intermolecular O-H⋯O hydrogen bonds link mol-ecules into chains along the b axis.