Introduction: Voice production and speech impairment in head and neck cancer patients can be experienced due to tumors or therapy such as radiotherapy. Velopharyngeal fibrosis in post-radiation nasopharyngeal carcinoma (NPC) patients can disrupt the velopharyngeal closure during speech, causing hypernasality. This study aims to determine the characteristics and proportions of the nasalance score in post-radiation NPC patients with or without resonance disorder. Materials and Methods: This research is a descriptive study using cross-sectional techniques, followed by retrospective data collection of post-radiation NPC patients at Dr. Cipto Mangunkusumo General Hospital for the period July-August 2023. The parameter assessed is the nasalance score using a nasometer, the velopharyngeal dysfunction assessed with flexible laryngoscopy, and the hypernasality assessed by a 15 years’ experienced speech therapist. Results: The nasalance score in the Gajah 1 test obtained a median of 14 (7-22), for the mean value of Hantu 1 test was 39.8% + 4.5, and for the mean value of Sengau test was 62.2 + 6.9, with a nasalance score cut point in Gajah 1 test between normal resonance and hypernasal was 15.5% and in Hantu 1 test was 42.5%. Gender and radiation dose to the pharyngeal constrictor muscle tend to have a significant relationship with resonance disorder in post-radiation NPC patients. Conclusion: A prospective study is needed in NPC patients with pre-and post-radiation assessment and follow-up evaluation to assess the effects of radiation which includes all relevant functional aspects of voice and speech. © 2025, Malaysian Medical Association. All rights reserved.