Toad venom, namely, "Chansu" in China, has been widely used for the treatment of heart failure, sores, pains, and various cancers. Upon LC-MS analysis of the venom from Bufo melanosticus collected in Indonesia, new bufadienolide sulfates were identified. For a complete characterization, the MeOH extract of the toad venom from B. melanosticus was fractionated by preparative HPLC, and the structures of five new buadienolide sulfates (1-5) along with one new bufogenin (6) were rapidly elucidated on the basis of LC-DAD-MS(n) and LC-SPE-NMR data. The in vitro growth inhibitory activity of these six compounds along with hellebrin (positive control) has been assayed by means of the MTT colorimetric assay in four human and two mouse cancer cell lines. Compound 3 and hellebrin displayed similar and marked in vitro cytotoxicity.