Subacute toxic encephalopathies are challenging to identify due to their often insidious tempo of evolution, nonspecific manifestations, relative infrequency as individual entities, and frequent lack of specific diagnostic testing. Yet they are crucial to recognize—in aggregate, subacute toxic encephalopathies are a common problem that can lead to severe, irreversible harm if not diagnosed and treated efficiently. This article reviews the clinically relevant aspects of some of the more important subacute toxic encephalopathy syndromes caused by inorganic toxins, carbon monoxide, antibiotics, antineoplastic agents, and psychiatric medications.