Small infarcts in the subcortical area (lacunar infarction) have been considered a relatively simple condition. In most cases, complications associated with warfarin are not a cause for worry, the superiority of angioplasty or stenting need not be disputed, and performing craniectomy is unnecessary; we simply administer an antihypertensive drug and aspirin. However, small subcortical infarcts are not easy to manage. No solid evidence has been presented to support the effectiveness of antiplatelet agents or statin, while the incidence of hemorrhagic complication after the use of antiplatelets is high in this condition. More importantly, the consequences of accumulated small vessel diseases are dismal; many patients suffer from progressively worsening gait difficulty and cognitive/emotional problems. The presence of small vessel disease even worsens the outcome of other stroke subtypes. Last, although genetic causes of small vessel disease are being studied, the existing knowledge on its pathogenesis, diagnosis, and treatment is far from satisfactory.