Tongue reduction surgery (TRS) has been advocated for children who have macroglossia associated with Beckwith Wiedemann Syndrome (BWS) to overcome, or reduce, the secondary effects of macroglossia. There are few reports describing the speech and oral motor characteristics in BWS, and no studies have systematically reported outcomes both pre- and post-operatively. The aims of this retrospective study were therefore to: systematically describe the speech and oral motor characteristics of this population pre- and post-operatively; to ascertain the effect TRS has on speech and oral motor skills and to discuss the presence of additional factors which may influence speech, and oral motor outcomes. Ten children with clinically confirmed BWS were assessed using a variety of standard clinical measures pre-operatively, three months post-operatively and at long-term follow up (mean age at follow-up after surgery 4.4 years). Results revealed that pre-operatively, speech was predominantly characterized by linguolabialization of bilabial consonants, and lingual blade production of alveolar and palatoalveolar consonants. These findings suggest that there are distinct articulatory errors caused by macroglossia. These errors were subsequently eliminated by TRS. Normal oral motor skills were present pre-operatively, and functional oral motor skills were found post-operatively with the exception of one case with co-occurring neurological impairment. Speech impairment unrelated directly to the macroglossia also occurred in the cohort. Assessment measures should take other factors into account when considering the aetiology of speech and oral motor impairment in this population.