Four new cleistanthane diterpenoids, phyllaciduloids A-D (1-4), were isolated from the roots and stems of Phyllanthus acidus (L.) Skeels (Phyllanthaceae). Their structures were elucidated on the basis of extensive spectroscopic analysis. Phyllaciduloids B-D (2-4) present in their structures with ether bond between C-7 and C-16, which were rarely reported. All the isolates were evaluated for their cytotoxic activities against five human cancer cell lines.