The paper considers the epidemiology and general etiological characteristics of cryptogenic stroke (CS). It discusses the concept of embolic stroke with an unknown source of embolism. It also characterizes the most significant causes of CS, such as paroxysmal atrial fibrillation, atrial cardiopathy, aortic atheroma, non-stenotic cerebral atherosclerotic plaques, and malignant neoplasms. The paper describes approaches to the diagnosis and secondary prevention of CS and proposes etiological and neuroimaging diagnostic algorithms for CI. Clinical cases are also presented.