The nucleoside, 9β-(2-deoxy-D-ribofuranosyl)-2-methoxyadenine [2], previously unknown as a natural product, has been isolated from a sponge in addition to the known nucleoside 9β-D-ribofuranosyl-2-methoxyadenine (spongosine) [1]. Thymine and 2-methoxyadenosine were also isolated from this sponge as a mixture. Nucleosides with biological activity have been isolated from a variety of marine sources (1,2). The potent antifungal activity demonstrated by toyocamycin (3,4) prompted our investigation of nucleosides from sponges. We have examined a sponge collected from Western Australia, and have isolated two nucleosides, spongosine [1], originally reported by Bergmann from Cryptotethya crypta (Hadromerida) (5-7), and 2'-deoxyspongosine [2]. Compound 2 has previously been obtained as a synthetic product (8), but this is the first report of it as a natural product. We also present herein completely assigned nmr spectral data for both 1 and 2 for the first time.