Objective: To test the sensitivity to change of the Outcome Measures in Rheumatology Clinical Trials (OMERACT) ultrasound (US) scoring system for tenosynovitis when applied in a multicenter design. Methods: RA patients with US-verified tenosynovitis were recruited when scheduled for treatment intensification. Tenosynovitis was assessed at baseline, and 3 and 6 months followup, using the semiquantitative OMERACT scoring system. Results: Expressed in median (25th; 75th percentiles), the overall greyscale and Doppler score decreased significantly from baseline at 4 (2; 7) and 3 (2; 6), to 6 months at 2 (0; 3) and 0 (0; 1, p < 0.01), respectively, and showed high responsiveness (standardized response mean = 0.8). Conclusion: The OMERACT US scoring system for tenosynovitis showed high responsiveness, supporting its use for diagnosing and monitoring tenosynovitis in multicenter trials.