A new sphingosine (1) was isolated from the MeOH extract of a marine sponge Haliclona (Reniera) sp. by bioactivity-guided fractionation. The 1D and 2D NMR, and MS spectroscopic analyses were used to establish the planar structure of 1. The stereochemistry of the compound was defined on the basis of modified Mosher`s method, comparison of optical rotation and NMR data with those of the reported. Compound 1 was mildly cytotoxic to a panel of five human solid tumor cell lines.