BACKGROUND: Lumbar disk prolapses are among the most common neurological conditions. In this open study, we asked whether repeated end-range spinal movements (McKenzie method) as physiotherapy in patients with lumbar disk prolapse induce early changes in location, size and signal intensity of lumbar disc material detectable by magnetic resonance imaging (MRI). We compared clinical with radiographic changes. The clinical efficacy of mechanical physiotherapy according to the McKenzie method within 5 days was documented. METHODS: Eleven consecutive patients with lumbar disk prolapse were included. Patients were treated with repeated end-range spinal movements and MRI was performed before and after 2-5 treatments. RESULTS: All patients achieved a reduction in symptoms and signs of disk prolapse during and after these procedures but none showed any change in the MRI features of the prolapses. CONCLUSIONS: Beneficial effects of specific mechanical physiotherapy in patients with radicular syndromes from lumbar disk prolapse are not paralleled by changes in the MRI appearance of the prolapses. Alternative explanations for the early clinical responses in some patients with lumbar disc prolapse treated according to the McKenzie method must be sought.