Trisomy 18 is a disorder characterized by psychomotor disabilities, dysmorphic features and organ malformations, including mental disabilities, growth deficiency, poor motor ability, micrognathia, microcephaly, low-set and malformed ears, distinctively clenched fists with overlapping fingers, and congenital heart defects. The prognosis is poor: 90% of infants with trisomy 18 do not survive beyond the first year of life and 99% die before the age of 10. This paper reports on a 13-year-old child diagnosed with trisomy 18. The major clinical features are cleft lip/palate, high-arched narrow palate, micrognathia, anterior open bite, posterior crossbite and taurodontism. Dental care management of these patients with special needs is discussed and the dental treatment for this child with trisomy 18 is described.