The peak at 3.35 ppm in the 1H-NMR spectrum characteristic for scyllo- inositol may be a marker for cerebral pathology, although it has a well- known constant concentration relative to myo-inositol. Such a peak was observed with an intensity at least 300% above normal in the brain of a healthy volunteer. The scyllo-inositol signal was assigned based on the detection of a corresponding peak at 74.5 ppm in the 13C-NMR spectrum and on the demonstration of singlet characteristics of the proton signal. The presence of substantial brain concentrations of scyllo-inositol suggests that scyllo-inositol metabolism may be regulated independently from myo-inositol and that such concentrations are compatible with normal health.