Ten new (1, 4-6, 9-14) and four known (2, 3, 7, 8) diacetylenes have been isolated from a brine shrimp active fraction of the methanolic extract of the stony coral Montipora sp. The structures were determined by combined spectroscopic methods. The compounds exhibited significant cytotoxicity against a small panel of human solid tumor cell lines. Montiporyne A (15), a previously reported congener, was also found to induce apoptosis in human colon tumor cell.