Aim: To study Danish physiotherapists' management of low back pain in the light of the report "Low back pain", published in 1999 by the Danish Centre for Evaluation and Health Technology Assessment (DACEHTA). Method: Two hundred and forty-two physiotherapists nationwide registered during 4 weeks in May 1999 consecutively all patients with "low back pain"; 4725 patients were registered representing a total of 12387 contacts. Reason for encounter, results of examination, exercise and treatment programme were registered. Results: In 94% of the consultations at least one of the recommended treatments was used, while 22% of the consultations involved ultrasound and short-wave diathermy, which are not recomended treatments. The McKenzie approach was used most frequently in patients with acute low back pain with radiation (odds ratio 3.1). Soft-tissue manipulation was given in 72% of the consultations. Sex of the physiotherapist was significant for choice of treatment. Discussion: The study shows that Danish physiotherapists' management of patients with low back pain is rationally founded. There seems, however, to be an over-use of passive treatment forms such as ultrasound, short-wave diathermy and heat and cold treatment, and continued quality development within the field is recommended.