A new solvent-tolerant species, Staphylococcus aureus, was isolated and characterized during the screening of butanol-tolerant microorganisms. Three isolates of S. aureus were obtained as contaminants during improvement of butanol tolerance of E. coli K12. Their cell dry weights were 135 % that of K12 in the absence of butanol stress. S. aureus had a growth advantage over K12 when cultured with various concentrations of butanol. It can tolerate up to 3 % (v/v) butanol, while most solventogenic bacteria can tolerate only 2 % (v/v) butanol. The addition of 10-20 g glucose/l enhanced its butanol tolerance. The relative cell biomass of the S. aureus was 71-306 % that of E. coli under 5.5-10 % (v/v) ethanol stress, indicating ethanol resistance. This is the first study to observe butanol-tolerant S. aureus. As this organism can be genetically manipulated, it could have a wide array of applications.