The acetoacetate fraction partitioned from Aloe vera L. showed an effective antibacterial activity against four clinically frequent pathogenic bacteria. Through a series of chromatographic methods and activity assays, one compound was obtained and it has potent antibacterial activity. Based on the data of mass spectrometry, 1H-NMR, 13C-NMR and IR spectra, this compound was determined to be fumaric acid. This study concluded that fumaric acid is one of the antibacterial components in A. vera.Key words: Fumaric acid, Aloe vera, antibacterial activity.
