Introduction: The purpose of this study was to investigate whether patient, tumor and radiation therapy factors are associated with development of middle ear effusion (MEE) in nasopharyngeal carcinoma (NPC) patients. Methods: A retrospective review of NPC patients treated between January 2000 and June 2018 at Rabin Medical Center. Patient factors, tumor factors, radiation doses and radiation fields were collected and outlined if needed (middle ear, eustachian tube (ET), tensor veli palatini (TVP) and levator palatini (LVP) muscles), then analyzed and compared between patients with MEE and those without and between sides in patients with unilateral MEE. Results: 73 patients were enrolled. Most were males (71.2%) with advanced stage diseases (78%). At the time of diagnosis 14 patients (19.2%) presented with MEE and in 18 (24.6%) patients post radiation MEE was observed (15 ipsilateral to the tumor and 3 bilateral). Tumor stage, histology and laterality were not associated with development of MEE. Comparison of mean radiation field dosages including - gross target volume (GTV), clinical target volume (CTV) and patient target volume (PTV) showed no association with post radiation MEE. In addition, no difference was found in the radiation doses to the middle ear, ET or the LVP nor the TVP between ears with and without MEE. Conclusions: Postirradiation MEE remains a common adverse effect in NPC patients. Surprisingly, tumor stage, tumor laterality and histology were not associated with MEE. Similar findings were observed for total radiation doses and specific doses to the middle ear, ET and ET muscles.