Colorectal cancer is the third most lethal and fourth most commonly diagnosed cancer worldwide. Sinapic acid, a derivative of hydroxycinnamic acid, is a promising phytochemical exhibiting numerous pharmacological activities in various systems. It is a substantial chain-breaking antioxidant that operates as a radical scavenger. The aim of this research was to investigate the antiproliferative effect of sinapic acid on the HT-29 cell line, besides the mechanisms underlying this activity. The effect of sinapic acid on the viability of HT-29 cell line was investigated using XTT assay. the levels of BCL-2, cleaved caspase 3, BAX, cleaved PARP and 8-oxo-dG were measured using ELISA. Gamma-H2AX and cytochrome C expression was assessed semi-quantitatively using immunofluorescence staining. Sinapic acid at 200 μM and higher doses produced a significant antiproliferative effect on HT-29 cells. The IC50 value was found to be 317.5 μM for 24 hours. Sinapic acid (317.5 μM) significantly elevated cleaved caspase 3, BAX, cleaved PARP and 8-oxo-dG levels. the levels of γ-H2AX foci are significantly higher while the levels of cytochrome-C are lower in sinapic acid treated HT-29 cells. These results indicate that sinapic acid has an antiproliferative, apoptotic and genotoxic effect on colon cancer cells.