Several new (E) stilbenes were synthesized by a combination of a Wittig olefination followed by Mizoroki-Heck coupling reactions. These compounds were screened for antitumor activity in a panel of 8 human cancer cell lines by a colorimetric SRB assay. Several of these compounds exhibit strong cytotoxicity. The most active compound of this series showed an average IC(50) value of 0.03 μmol; it acts by apoptosis as shown by a dye-exclusion test, an extra acridine orange/ethidium bromide staining and DNA-laddering experiments.