Small ischemic foci of 15mm in the brain are usually not a serious condition. Due to the relatively small ischemic foci, they have less impact on the brain and usually do not show obvious clinical symptoms. Ischemic foci are manifestations of the effects of chronic hypoxia in the brain, usually detected by cranial CT or MRI, and can be clinically asymptomatic, or can present with symptoms of chronic ischemia in the brain, such as dizziness, memory loss, and so on. The main reason for the occurrence of ischemic foci is atherosclerosis. The occurrence of atherosclerosis is usually associated with numerous risk factors, such as smoking, hypertension, hyperlipidemia, diabetes mellitus, obesity, mental stress, sleep and so on. Related risk factors should be controlled in general to avoid the occurrence and progression of atherosclerosis, thus preventing further progression of ischemic foci in the brain. When ischemic foci in the brain are detected, prompt medical consultation is recommended.