Esophageal leiomyoma derived from the muscularis mucosae (MM) is a rare condition, and the optimal modality for diagnosis and treatment is controversial. Endoscopic ultrasonography can provide an accurate image of esophageal layer structure, providing information on lesion suitability for potential endoscopic therapy. We attempted to investigate the diagnostic value of a transendoscopic balloon-tipped miniature ultrasonic endoprobe for small esophageal leiomyomas derived from MM. We resected 7 small esophageal leiomyomas derived from MM by endoscopic mucosal resection (EMR), all of which were diagnosed by a balloon-tipped endoprobe. The endosonographic and pathologic features of 7 cases of small esophageal leiomyomas derived from MM were compared. The balloon-tipped endoprobe clearly showed all 7 small esophageal leiomyomas derived from MM, even those under 5 mm in size (smallest lesion, 3.0 mm). The endosonographic characteristics of small esophageal leiomyomas derived from MM were a hypoechoic mass with smooth, regular, and a well-defined outer margin and homogenous inner echogram arising from the second hypoechoic layer. Complete resections were possible in all 7 cases by EMR without any complications. Tumor size was 3.0-13.5 mm (mean 7.8 mm) in maximum diameter. In all cases, endosonographic findings by endoprobe were exactly concordant with pathologic finding in determining the tumors depth in the esophageal wall, tissue origin and characteristics, growth pattern, and size. We detail the balloon-tipped endoprobe is a simple, convenient, and very useful in making accurate diagnosis of small esophageal leiomyomas derived from the MM and the appropriate applications of EMR.