Six compounds were purified from the extracts of fungus Z18-17 (Nigrospora sp.) isolated from Scyphiphora hydrophyllacea, a tree from the intertidal zone of Shankou, Guangxi Province of China, which was reported to have cytotoxic activity. Systematic study on the chemical constituents of Nigrospora sp. resulted in the isolation of one new 6-phenylhexanoic acid derivative, one new derivative of uridine, and four known compounds. Their structures were characterized, respectively, as methyl 5-acetamido-6-(4-hydroxyphenyl)-4-oxohexanoate (1), uridine-5'alpha-hydroxypropanoate (2), 4-hydroxyphenethyl 2-hydroxypropanoate (3), methyl pyroglutamate (4), cyclo (Pro-Val) (5), and cyclo (Phe-Hyp) (6). The cytotoxic activities of the two new compounds against HL-60 cell line were tested and the IC(50) values of the two new compounds were all over 100 muM.