Abstract. : The comprehensive, successful treatment of patients with cleft lip, alveolus and palate requires numerous surgical interventions and very close cooperation between various medical and dental specialists. The willingness and ability of the patient to undergo treatment are undoubtedly important factors in achieving optimal treatment outcomes. The presented case report shows that limited compliance makes it much more difficult for speech pathologists and orthodontists to treat mentally retarded patients. Only with combined orthodontic therapy and orthognathic surgery could the dental and skeletal abnormalities be corrected in adulthood.