Injury or bulging subepithelial mucosal lesions are covered with normal mucosa, usually asymptomatic. Most are diagnosed in radiology or endoscopy, which may correspond to any layer of the body wall (intramural) or non-belonging to the wall (extramural). This article describes studies for analysis of endoscopic ultrasonography (EUS) as a diagnostic method with high accuracy on the finding of subepithelial lesion. The authors review the literature on the endoscopic ultrasound features of subepithelial lesions and differentiation in intra-or extramural, source layer, echogenicity, vascularity, size and margins, fine needle aspiration (FNA) and needle biopsies of type "trucut" for histological analysis. The EUS has the best combination of accuracy in the diagnosis of gastrointestinal wall layer compromised by lesions or masses, besides studying the echogenicity of the lesion, which helps in differential diagnosis. EUS is safe and detailed, considered the best imaging for definitive diagnosis and therapeutic planning of subepithelial lesions.