During the past 2 years, 40 patients referred to the authors' hospital for persistent calcifying tendinitis of the shoulder were seen on prospective followup after undergoing a single extracorporal shock wave therapy. During a single therapy session, all patients received 1500 impulses of the energy density 0.28 mJ/mm2 in plexus anesthesia. Followup examinations were done at 6 and 24 weeks. In 62.5% of the patients partial or complete disintegration of the deposit was observed. Statistical analysis showed significant improvement both of subjective and objective criteria. According to the Constant score, 60% of the patients reached normal values, and 72.5% of the patients had no or only occasional discomfort. Only 6 patients (15%) reported no improvement at the 24-week followup.