In a blinded randomized clinical trial, we compared the effectiveness of manual therapy, physiotherapy, (continued) treatment by the general practitioner (GP), and a placebo therapy (detuned ultrasound and detuned short wave diathermy) for patients (n = 256) with chronic nonspecific back and neck complaints. The physical outcome measures (spinal mobility and physical functioning) are presented for 3, 6 and 12 wk follow-up. Manual therapy showed a faster and larger improvement in physical functioning compared to the other three therapies. The changes in spinal mobility among the four study groups appear to be small and show no consistent pattern.