Objective: To describe and compare the demographic and clinical characteristics of patients with acute or chronic low back pain across all health care settings treating this condition.Design and setting: Concurrent prospective survey registration of all consecutive consultations regarding low back pain at general practitioners, chiropractors, physiotherapists, and the secondary care spine centre in Southern Denmark.Subjects: Patients ≥16 years of age with low back pain.Main outcome measure: Demographic characteristics, symptoms, and clinical findings were registered and descriptively analysed. Pearson's chi-square tested differences between the populations in the four settings. Multiple logistic regression assessed the odds of consulting specific settings, and t-test assessed differences between patients attending for a first and later consultation.Results: Thirty-six general practitioners, 44 chiropractors, 74 physiotherapists, and 35 secondary care Spine Centre personnel provided information on 5645 consultations, including 1462 first-visit consultations. The patients differed significantly across the settings. Patients at the Spine Centre had the most severe symptoms and signs and were most often on sick leave. Compared to the other populations, the chiropractor population was younger, whereas the physiotherapist population was older, more often females, and had prolonged symptoms. In general practice, first-time consultations were with milder cases while patients who attended for a second or later consultation had the worst symptoms, findings, and risk of sick leave compared to the other primary care settings.Conclusion: The demographic and clinical characteristics of patients with low back pain differ considerably across the health care settings treating them.KEY POINTSThe study describes the symptoms and clinical findings of patients with low back pain consulting the Danish health care system in all its settings.Patients with chiropractors were youngest, while those with physiotherapists were the oldest and most frequently female.First consultations in general practice were generally with the least symptomatic patients while those returning for a subsequent consultation had more severe disease including more sick leave compared to patients in the other primary care settings.Our findings call for caution when generalizing between health care settings for patients with low back pain.