This study examined paths to first treatment and the duration of untreated illness in 140 anorexia nervosa patients using validated questionnaires and a clinical interview. The differences between individuals with an early (≤14 years, n = 40), intermediate (15–18 years, n = 53) and late onset (≥19 years, n = 47) were investigated. Participants were most commonly informed about their diagnosis and first treatment facility through general practitioners and paediatricians. The duration of untreated illness exceeded 2 years in the complete sample (25.14 months) and was longest for individuals with an early onset. The early onset group was more often externally vs. internally motivated and more frequently informed about treatment options by their social network, e.g. parents, than patients with a late onset. The results emphasize the relevance of training general practitioners and paediatricians about anorexia, the need to include parents and teachers in eating disorder prevention and to improve targeting young individuals in early interventions. Copyright © 2014 John Wiley & Sons, Ltd and Eating Disorders Association.