Velopharyngeal insufficiency (VPI) is a well recognized but rare complication of adenoidectomy. Twenty children with this condition were seen and assessed at Great Ormond Street Hospital between 1993 and 2000. The commonest aetiology was occult submucous cleft palate (n = 5) but there was a wide range of other causes. Two children with severe behavioural disorders and normal palates developed mild symptoms, an aetiology not previously reported. Only two children had a classical submucous cleft palate. Nine children required surgical intervention and three revision procedures. Of the 15 treated children for whom follow-up data was available, 13 regained normal or near-normal speech. Many cases of postadenoidectomy VPI was not foreseeable. Following referral to a specialist cleft unit, normal or near-normal speech can be achieved in the majority with a combination of surgery and speech therapy.