One challenge for designing drugs to treat Alzheimer's diseases is to identify compounds that are effective at binding to and preventing protein aggregation not only in vitro but also in vivo. This requires blood-brain barrier permeability at levels necessary to target these toxic aggregates. scyllo-Inositol, a compound that is naturally occurring in the body, has shown promise as an therapeutic both in vitro and in vivo. In TgCRND8 mice, which overexpress human APP, bearing two familial AD mutations, treatment with scyllo-inositol resulted in reduced Aβ pathology, a rescue of spatial memory and an increase in survival in transgenic animals. This review summarizes what is currently known about scyllo-inositol, it's biologically relevant synthesis, degradation and transport mechanisms at the tissue and cellular levels. scyllo-Inositol is currently in phase II clinical trials for Alzheimer's disease. Phase I clinical trials have shown that scyllo-inositol is well tolerated, with no significant adverse effects at all doses tested. Orally administered scyllo-inositol is able to cross into the CNS at levels that were therapeutically effective in animal models of Alzheimer's disease. Efficacy of this treatment paradigm will require evaluation of present and future human clinical trials.