Anthocyanidins induce apoptosis in some cancer cell lines, but studies describing the dose-dependent effects on cell populations are limited. My objective was to evaluate the dose-dependent response of malvidin and delphinidin, anthocyanidins with different chemical structures, on cell viability and apoptosis in HT-29 cells compared to curcumin, a known inducer of apoptosis. Lower concentrations of anthocyanidins increased cell viability by 12-16% compared to control. Higher concentrations of 80 umol/L of curcumin, malvidin, and delphinidin decreased cell viability by 16-44%. Apoptosis was assessed by measuring caspase-3 and caspase-8 activities, as well as mitochondrial permeability. Only high concentrations (80 umol/L) of anthocyanidins and curcumin increased caspase-3 and caspase-8 activity. Concentrations of 25, 50 and 80 umol/L malvidin and delphinidin significantly disrupted mitochondrial permeability, showing anthocyanidins may be more effective at inducing apoptosis intrinsically. There was a significant interaction between anthocyanidin concentration and anthocyanidin type on cell viability, caspase-8 activity, and mitochondria permeability.