The antioxidative and antimutagenic effects of a 80% methanol extract of Panicum miliaceum were examined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, determination of the total polyphenol content, and the Ames test using Salmonella typhimurium. The DPPH radical scavenging activity (EC 50) and total polyphenol content of the 80% methanol extract of P. miliaceum were 67.43±4.28 μg/mL and 16.26±1.02 mg/g, respectively. The 80% methanol extract was sequentially fractionated using chloroform, n-butanol, and water, and the chloroform fraction was found to exhibit strong antioxidative effects. The antimutagenic effects of P. miliaceum against aflatoxin B1, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole, and 2-aminofluorene were then studied by the Ames test using S. typhimurium TA98 and TA100. The results obtained using the 80% methanol extract (600 μg/plate) and S. typhimurium TA98 and TA100 showed 95.2±2.3 and 89.8±4.5% inhibition of mutations caused by AFB 1 , respectively. Similarly, the chloroform fraction (200 μg/plate) exhibited a >90% inhibition for both strains. These results therefore indicate that P. miliaceum exhibits both mutagenic and antioxidant activities, thereby rendering it suitable for use in a variety of food materials.