In vitro antioxidant and antimutagenic activity of dietary chlorophyll derivatives was assessed. Antioxidant activity was determined by the ability of each compound to scavenge the long-lived free radicals 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS+). Antimutagenic activity was assayed with a modified microscreen bacterial reverse mutagenicity assay using Salmonella typhimurium TA100 and benzo[a]pyrene as the tester strain and mutagen respectively. Derivatives of chlorophyll a were found to be more effective radical quenchers than those of chlorophyll b. Furthermore, metal-free derivatives such as chlorins, pheophytins, and pyropheophytins exhibited significantly lower antiradical capacity than metallo-derivatives such as Mg-chlorophylls, Zn-pheophytins, Zn-pyropheophytins, Cu-pheophytina, andCu-chlorophyllins. Both metal-free and metallo-chlorophyll derivatives demonstrated similar dose-dependent inhibitory activity against B[a]P induced mutagenesis. These results demonstrate that dietary chlorophyll derivatives prevalent in both fresh and processed foods and dietary supplements have antioxidant and antimutagenic activities.