Bioactivity-guided fractionation of the ethyl acetate-soluble fraction of a methanol extract of the fruits of Casearia grewiifolia afforded eight new clerodane diterpenes, caseargrewiins E-L (1-8), and a known clerodane diterpene, esculentin B (9). The structures of 1-8 were established on the basis of 1D and 2D NMR spectroscopic data. Most of these compounds exhibited cytotoxicity against three cancer cell lines with IC50 values in the range 0.15-6.00 microg/mL.