In a retrospective study, 217 patients with conservatively treated adolescent idiopathic scoliosis (AIS) were investigated. Forty-nine cases were operated and 168 were treated only conservatively and had been out of the brace for at least 4 years at the time of the investigation. The progression between cessation of brace treatment and follow-up (a mean of 6.9 years later) was 5.1°. Almost all progression (4.5°) occurred within 2 years of the end of weaning, however. The incidence of failure with regard to the length of follow-up was also studied. A follow-up of 2 years was sufficient to predict with great accuracy (97%) all incidences of failure.