The free radical scavenging ability of beta-carotene was studied using free radical 2,2-diphenyl-1- picryl-hydrazyl (DPPH). As the concentration of beta-carotene in acetone increased, the absorbance of DPPH at 517 nm decreased, which indicates that beta-carotene scavenges free radicals. It was shown that beta-carotene does not work as an antioxidant in soybean oil. The NMR spectrum of DPPH with BHA in CDCl3 showed a new peak at 5.0(d) was formed and the peak at 6.6(d) from BHA was split into 2 peaks, which may be due to the hydrogen atom donation from BHA to DPPH. The NMR spectra of DPPH with beta-carotene did not change during reaction and no peak was formed.