Evidence is presented that inStaphylococcus aureus mannitol is metabolized by phosphorylation to mannitol-1-phosphate and subsequent dehydrogenation to fructose-6-phosphate. Both mechanisms were equally active in a coagulase-positive and a coagulase-negative strain. Mannitol metabolism is inducible, both mannitol and sorbitol acting as inducers. No evidence for unphosphorylated mannitol breakdown could be found.