Macrostomia is a rare medical condition, defined as an enlargement of the mouth at the oral commissure.

Macrostomia is a form of a facial cleft. Macrostomia can present as a unilateral or bilateral anomaly with a partial or complete cleft. Associated anomalies of the surrounding bone, muscle and soft tissue can also be present with or without the presence of a syndrome.

Macrostomia results in aesthetic disharmony and also in functional problems. In both cases surgery is the treatment of choice. In cases of macrostomia, additional investigations should be performed to rule out accompanying cardiac and renal anomalies and associated syndromes. A multidisciplinary approach and good collaboration between healthcare providers is essential for optimal care of these patients.

The incidence varies between 1 in 60 000 to 1 in 300 000 live births.