Aim This non-randomized pre-post-intervention study investigated the effect of a systemic public health intervention on the length of time between anorexia nervosa symptom onset and contact with the health care system as well as the initiation of treatment. BACKGROUND: Although systemic public health interventions have successfully been implemented in physical and mental health fields, their effect on the early treatment of patients with anorexia nervosa remains unclear. METHODS: In total, 59 anorexia nervosa patients (mean age=21.5 years, SD=7.2) were recruited before a systemic public health intervention, and 18 patients (mean age=22.2 years, SD=8.9) were recruited afterwards. Using validated self-report measures and a semi-structured interview, the duration of untreated anorexia nervosa and the duration until first contact with the health care system were investigated. Findings At the beginning of the individual treatment initiation process, participants in both samples most frequently consulted their general practitioner or paediatrician about their eating disorder-related symptoms. Neither the mean duration of untreated anorexia nervosa, that is, the time between illness onset and the initiation of a recommended treatment, nor the duration until first contact with the health care system significantly decreased after the implementation of the systemic public health intervention. The mean duration of untreated anorexia nervosa was 36.5 months (SD=68.2) before the systemic public health intervention and 40.1 months (SD=89.4) after the implementation of the systemic public health intervention. The mean duration until first contact with the health care system was 25.0 months (SD=53.0) before the intervention and 32.8 months (SD=86.5) after the intervention. CONCLUSION: Primary care providers are crucial to the treatment initiation process and should be involved in future interventions to improve early detection and treatment commencement amongst patients with anorexia nervosa.