Monoamine oxidase (MAO) inhibitors have utility in ameliorating a variety of neurological conditions, including depression. R-(?)-Deprenyl is a selective, reversible inhibitor of MAO-B (Ki = 0.091 μM) over MAO-A (Ki = 9.06 μM). In addition to finding use against depression, R-(?)-deprenyl provides neuroprotection which may be relevant to Parkinson’s disease, Alzheimer’s disease, Huntington’s disease, and stroke. The ability of this compound to slow the progression of disability in early Parkinson’s disease may be independent of its effects on MAO activity.