Two new diterpenic glycosides, virescenosides M (1) and N (2), have been isolated from a marine strain of Acremonium striatisporum KMM 4401 associated with the holothurian Eupentacta fraudatrix. Their structures were determined on the basis of MS and NMR data as beta-D-altropyranosido-19-7-oxo-isopimara-8,15-diene-2alp ha, 3beta-diol (1) and beta-D-altropyranosido-19-isopimara-7, 15-diene-2alpha,3beta,6beta-triol (2). Three other altrosides (3-5), identified as virescenosides A, B, and C from the terrestrial strain Acremonium luzulae, were also isolated. The cytotoxic activity of the virescenosides was examined.