목적: Tongue base is a frequent anatomical obstructing point in obstructive sleep apnea. However little is known about the histopathologic features of the tongue base and its correlation with radiographic findings. Moreover there are few reports about the clinical impact of histopathologic character to OSA severity. The aim of this study was to investigate the histopathologic findings of the tongue base in patients with obstructive sleep apnea after transoral robotic surgery. 방법:Thirteen patients who underwent transoral robotic surgery were involved in this study. All the study patients were preoperatively diagnosed with OSA and showed tongue base level obstruction after upper airway evaluation. The histopathologic findings of the excised specimens were evaluated and matched with the computed tomography (CT) images. Correlation of the OSA severity (polysomnographic parameters AHI, lowest O2 saturation) with the microscopic findings of tongue base were analyzed. 결과:Most of the tongue base specimen had a four layer structure under light microscope, which were epithelial layer, lymphoid follicle layer, glandular layer and muscular layer. The depth of the layers which were measured under a microscopy were highly correlated to the matched layer depth in CT images (follicular layer p=<0.001, glandular p=0.073). However there was no association between the OSA severities with the microscopic findings. 결론:The base of the tongue was composed of four layers which were epithelial, lymphoid follicle, glandular and muscular layer. It is possible to assume the depth of these layers by estimating the CT images. However the severity of OSA was not correlated to these histopathologic findings.