No results on long-term outcome in terms of health-related quality of life (HRQL) have previously been presented for patients treated for adolescent idiopathic scoliosis. A consecutive series of patients with adolescent idiopathic scoliosis, treated between 1968 and 1977 before the age of 21, either with distraction and fusion using Harrington rods [surgical treatment group (ST), n=156; 145 females and 11 males] or with a brace [brace treatment group (BT), n=127; 122 females and 5 males] were followed at least 20 years after completion of the treatment. Ninety-four percent of ST and 91% of BT patients filled in a questionnaire comprising the SF-36, Psychological General Well-Being Index (PGWB), Oswestry Disability Back Pain Questionnaire, parts of SRS/MODEM'S questionnaire and study-specific questions concerning the treatment, as a part of an unbiased personal follow-up examination including radiography and clinical examination. An age-and sex-matched control group of 100 persons was randomly selected and subjected to the same examinations. The results showed no differences in terms of sociodemographic data between the groups. Both ST and BT patients had a slightly, but significantly, reduced physical function using the SF-36 subscales, SF-36/Physical Component Summary (PCS) score as well as the Oswestry Disability Back Pain Questionnaire compared to the controls. Neither the mental subscales and the Mental Component Summary (MCS) score of SF-36 nor the PGWB index showed any significant difference between the groups. Forty-nine percent of ST, 34% of BT and 15% of controls admitted limitation of social activities due to their back [P<0.001 ST vs controls, P=0.0010 BT vs controls, and n.s. (P=0.024) ST vs BT], mostly due to difficulties with physical participation in activities or selfconsciousness about appearance. Pain was a minor reason for limitation. No correlation was found between the outcome scores and curve size after treatment, curve type, total treatment time or age at completed treatment. Patients treated for adolescent idiopathic scoliosis were found to have approximately the same HRQL as the general population. A minority of the patients (4%) had a severely decreased psychological well-being, and a few (1.5%) were severely physically disabled due to the back.