The use of an adenoid curette of appropriate size is recommended in operative textbooks for adequate adenoid removal and avoidance of potential injury to the eustachian tubes. The aim of this study is to calculate the right size of adenoid curettes to be used for children of different ages. The inter-tubal space (ITS) between the torus tubarius on both sides is the narrowest passage for adenoid curettage, and is identified in this study as the nasopharyngeal dimension to be considered in selecting the size of the adenoid curette. This prospective study is carried out on a series of 72 adenoidectomy cases aged from three to nine years at the Hearing and Speech Institute in Cairo, Egypt. The inter-tubal dimension (ITD) is measured for each child at the end of adenoidectomy and the results are recorded against the patient’s age. The ITD ranged from 17–21 mm in our series with no significant difference between males and females. There is an increase in ITD with age with a sharp increase at ages five and seven years. Accordingly, the patients are divided into three age groups and recommendations for appropriate adenoid curette sizes ranging from 18 to 21 mm are given for each group.