The capsule endoscope (CE) and the double-balloon endoscope (DBE), were developed to visualize the entire small intestine, have substantially altered diagnostic options in patients with small intestinal diseases. The CE provides clear, natural images of the entire small intestine and allows for the visualization of even minute lesions, such as solitary red spots and minor erosions. However, the major disadvantages of the CE are that it sometimes fails to reach the cecum, can become trapped in the intestine, and does not allow biopsy or treatment. The DBE can reach beyond the ligament of Treitz when inserted orally, and can reach beyond the ileocecal valve when inserted anally; therefore, real-time visualization of the entire small intestine is possible when the oral and anal approaches are combined. The DBE provides sharp endoscopic images, but its main advantage lies in its four-directional angle of operation and special instrument channel that allow both directed biopsies and treatments, such as the resection of polyps and the dilation of strictures. However, the major disadvantages of examination with the DBE when compared with the CE are that it requires sedation, often requires fluoroscopy, and cannot be performed without additional support staff. Therefore, the CE can be used to screen for small intestinal pathologies, and the DBE can be used for the optimal diagnosis and treatment of these diseases. Both the CE and DBE should be established as gold standards in the diagnosis and treatment of small intestinal lesions.