A new carbazole alkaloid, antipathine A (1), together with three known zoanthoxanthin alkaloids (2--4) was isolated from the EtOH/CH2Cl2 extracts of the South China Sea black coral Antipathes dichotoma. The structure of 1 was determined on the bases of extensive spectroscopic analysis, including 1D and 2D NMR data. Compounds 1 and 2 showed moderate cytotoxicity against human stomach carcinoma SGC-7901 cell line with IC50 of 67.38 and 86.40 microg/ml, respectively, and 1 and 2 also showed weak cytotoxicity toward human liver carcinoma Hep_G2 cell line.