We report the case of a 24-years-old man with parcellar Complex Regional Pain Syndrome I (CRPS I) of the patella, responsible for major functional limitation. The diagnosis was based on physical exam and X-ray, in the absence of other articular or peri-articular diseases. The patient received two pamidronate perfusions over a week, with a spectacular decrease of pain, which allowed him to follow the rehabilitation program in good conditions. He was therefore able to go back to work. The place of this treatment in CRPS I is discussed.