The function of the tensor and levator veli palatini muscles was examined electromyographically in 26 patients with cleft palate, before and after Le Fort I-osteotomy. Hearing ability was determined audiometrically and via tympanometry and the maxillary advancement determined three dimensionally on the basis of model operation and lateral teleradiography. Due to the operative oedema, temporary functional impairment in palatal muscle tissue and sound transmission ability in the middle ear can occur. In several cases, maxillary osteotomy produced an improvement in ventilation of the middle ear and also improved the muscular activity of the palate in cleft patients.