We report a prospective study of the effects of extracorporeal shock-wave therapy in 195 patients with chronic calcifying tendinitis. In part A 80 patients with chronic symptoms were randomly assigned to a control and three subgroups which had different treatment by low-energy and high-energy shock waves. In part B 115 patients had either one or two high-energy sessions. We recorded subjective, functional and radiological findings at six months after treatment. The results showed energy-dependent success, with relief of pain ranging from 5% in our control group up to 58% after two high-energy sessions. The Constant scores and the radiological disintegration of calcification were also dose-dependent. Shockwave therapy should be considered for chronic pain due to calcific tendinitis which is resistant to conservative treatment.