Background/Aim: We examined the diagnostic performance of the tongue protrusion with phonation and open mouth (TOPPOM) method for visualizing structures of the oropharynx. Patients and Methods: Transoral endoscopy was performed on 20 healthy participants to evaluate 12 oropharynx subsites under three conditions: open mouth (OM), phonation with open mouth (POM), and TOPPOM. Each subsite was scored from 0 to 2 depending on subsite visualization, and the scores were summed. Images of subsite-adjacent mucosa were similarly scored. Results: The total scores were significantly higher for TOPPOM than for POM and for POM than for OM. Such scores were observed for both the palatine arches, both palatine tonsils, the left lingual tonsillar sulcus, and the vallecula. Conclusion: TOPPOM enables visualization of the oropharynx through transoral endoscopic examination, and TOPPOM with conventional transnasal endoscopy may enable early detection of oropharyngeal carcinomas and lesions and improve the performance of pre- and post-treatment evaluations.