Substantial development in equipment such as miniprobe endosonography and enteroscopy has made it possible to use endoscopic ultrasonography (EUS) to detect any part of the digestive tract. EUS plays a vital role in evaluating a lower intestinal malignancy, particularly rectal cancer, to determine whether the disease is localized (T1-2, N0) and appropriate for surgery or locally advanced (T any, N1-2) and would benefit from preoperative neoadjuvant chemoradiation. Moreover, follow-up by EUS may contribute to early recognition of focal tumor recurrence, particularly for lesions that cannot be detected by other imaging modalities. EUS is also an invaluable modality for diagnosing intestinal submucosal tumors, such as gastrointestinal stromal tumors, lipomas, lymphangiomas, leiomyomas, carcinoids, and others such as intestinal endometriosis. Although a definite diagnosis of a submucosal tumor is generally confirmed by cytology or histology results, EUS-guided fine needle aspiration or core biopsy is a fairly helpful practice. EUS is also useful for discriminating between Crohn's disease and ulcerative colitis as well as assessing disease severity. Moreover, it has emerged as a powerful imaging tool to manage perianorectal diseases. EUS also has the potential to be useful for intra-small intestinal ultrasonography for the diagnosis of small bowel diseases in the future.