Marine microorganisms have proved to be rich sources of bioactive secondary metabolites, and numerous compounds with potent biological activities and unique chemical structures have been isolated [1]. In the course of our search for novel bioactive compounds from marine mangrove fungi [2–6], the extract of the endophytic fungus No. 1893 was found to exhibit cytotoxicity toward NCI4460 and Bel-7402, and high activities against Heliothis armigera (Huehner) and Sinergasilus spp. This endophytic fungus strain was collected from the dropper of Kandelia candel from an estuarine mangrove on the South China Sea coast. Two new lactones 1893A and B have been isolated from its fermentation broth [7], which have attracted one group to synthesize them since their report [8]. In the ongoing research on metabolites from the fungus we adopted industrial fermentation to replace experimental fermentation. A new compound, 6-hydroxy-3-methylisochroman-5-carboxylic acid (1), together with six known compounds, mycoepoxydiene (2) [9], 5-carboxylmellein (3) [10], 5-methylmellein (4) [11], pyrrole-2 carboxylic acid (5) [12], 3-methylhydantoin (6) [13], and cyclo(L-Ala-L-Tyr) (7) [14] were isolated from the fermentation broth of this fungus. Compound 2 was the analog of 1893A and B. Their structures were elucidated by spectroscopic methods.