The anti-colon cancer effect of dietary fibre results in part from its fermentation into the short-chain fatty acid butyric acid (BA) by intestinal microflora. BA has potent anti-colon cancer properties owing to its ability to induce apoptosis in colon cancer cells. The colon is not the only location where BA may reach high concentrations, because dietary BA is rapidly absorbed and transported to the liver. We have investigated whether BA could induce apoptosis in transformed human liver (Hep G2) cells. Hep G2 cells treated with BA displayed acetylated histones, increased DNA fragmentation and morphological features consistent with apoptosis. These biochemical features of BA-treated liver cells are identical to those of BA-treated colon cells. In addition, we investigated whether BA present in tributyrin, a triacylglycerol more compatible for inclusion into colloidal lipid structures than BA, could also induce apoptosis in Hep G2 cells. Tributyrin induced DNA fragmentation and morphological features characteristic of apoptotic cells in Hep G2 cells. These results are a significant advance towards delivering BA via colloidal lipid particles to cancerous sites in vivo. This study showed that BA and tributyrin are potent apoptotic agents, and we suggest that sources of dietary BA, such as milk fat, may provide anti-liver cancer properties.