A systematic examination of the Chinese soft coral Dendronephthya sp. resulted in the isolation and characterization of 18 new cembranoid diterpenes, namely, dendronpholides A-R (2-19), along with 11-episinulariolide and an enantiomer of sandensolide. Their structures were determined through extensive spectroscopic (IR, MS, 2D NMR) data analyses and by comparison with those reported in literature. The cytotoxicity of several compounds against human tumor cell lines was also evaluated.