Leukoaraiosis (LA) means decreased density of the white matter of brain. It is seen as hypodensity on computed tomography (CT) scans and as hyperintensity on T2-weighted magnetic resonance imaging (MRI) scans. When Hachinski et al. [1] coined the term in 19 87, it referred to the diffuse or patchy hypodensities seen in the deep white matter on CT scans of elderly people. Others, however, included all kinds of hypodensities of the white matter and often labeled it Binswanger''s disease. It was uncertain what these hypodensities were and whether they had any clinical significance. MRI white matter hyperintensities may be: (1) punctate ''holes'' in the deep ganglia and white matter; (2) smooth ''rims and caps'' contiguous with the margins of the lateral ventricles, or (3) patchy areas in the deep white matter of the centrum semiovale extending to the vicinity of the subcortical regions but sparing the U fibers. What is LA and how does it relate to cognition? We asked several experts to offer their opinions on the linkage between cognitive functions and LA. We informed each one that we do not expect new data, detailed analyses, or an authoritative review. Rather, we wanted their concise views on the subject. Their opinions follow.