To investigate the causes of persistent, apparently permanent hypernasal speech following adenoidectomy in 10 subjects without overt cleft palates, and to establish a protocol to be followed before this operation is performed.Retrospective and descriptive design.Ten subjects, fulfilling the following criteria, were included: (i) subjects had undergone adenoidectomy which resulted in hypernasal speech that persisted for longer than 3 months (and was therefore considered to be permanent); (ii) subjects did not have a cleft lip or overt cleft palate; (iii) there was no hearing loss of sufficient magnitude to account for the hypernasal speech; and (iv) the hypernasality was rated as severe by a speech therapist, could not be remedied by speech therapy alone and required further management by a plastic surgeon through pharyngosplasty. Ten subjects were found through the clinical records of speech therapists and plastic surgeons working in hospitals and private practice. The following information was obtained through interviews or by reading the case files: (i) identifying information; (ii) the presence of any of the factors reported in the literature to be associated with the permanent hypernasality or nasal emission, as well as the method of identification; and (iii) whether these factors had been identified before or after the adenoidectomy.Nine out of a total of 10 subjects showed preoperative perceptual and structural characteristics and/or case history factors that have been documented to constitute risk factors for the development of nasal speech, should an adenoidectomy be performed. The methods used to investigate these factors pre-operatively appear to have been inadequate.This undesirable sequel to surgery can be prevented if certain case history and speech factors are investigated and followed up with radiographic procedures if necessary.