Five new metabolites including four β-resorcylic macrolides 1–4 and one octahydronaphthalene derivative 5 were isolated from a seagrass-derived fungus Fusarium sp. PSU-ES123 together with seven known compounds. Their structures were characterized by analysis of the spectroscopic data. The absolute configuration was determined by Mosher's method and circular dichroism spectroscopy. Compound 1 displayed