Scoliosis in trisomy 18. Patients with trisomy 18 typically present with multiple congenital anomalies and most die within the first year. However, long-term survivors are not uncommon. Seventeen patients with trisomy 18 were evaluated to study the development of scoliosis associated with this disorder. There were 13 females and 4 males with ages ranging from birth to 22 years. Twelve patients died by age 2. None developed scoliosis or had vertebral anomalies. The five patients who survived beyond age 2 developed scoliosis. Curve progression was demonstrated in the patients who returned for follow-up. Bracing was not well tolerated in two patients with curves of 48 degrees and 58 degrees. Both had poor motor control and sitting ability. One patient with a 30 degree curve was successfully managed by bracing. Another patient with a severe scoliosis was successfully fused with anterior and posterior instrumentation. Patients with trisomy 18 should be carefully evaluated for scoliosis. Scoliosis in the older child, surviving beyond age 2, may be progressive and difficult to manage. 