Gram-negative bacteria exhibit lipopolysaccharides (LPSs) on their outer membrane surface. LPS is considered one of the most potent bacterial virulence factors. Here we report the elucidation of the LPS O-chain structure isolated from Burkholderia fungorum, a bacterium isolated from the white-rot fungus Phanerochaete chrysosporium that can act as a pathogen for plants and domesticated animals. The structure was determined by the employment of detailed chemical and NMR spectroscopy analyses as the following.