BACKGROUND: Shock wave therapy has seen widespread use since the 1990s to treat various musculoskeletal disorders including rotator cuff disease, but evidence of its efficacy remains equivocal. OBJECTIVES: To determine the benefits and harms of shock wave therapy for rotator cuff disease, with or without calcification, and to establish its usefulness in the context of other available treatment options. SEARCH METHODS: We searched Ovid MEDLINE, Ovid Embase, CENTRAL, ClinicalTrials.gov and the WHO ICTRP up to November 2019, with no restrictions on language. We reviewed the reference lists of retrieved trials to identify potentially relevant trials. SELECTION CRITERIA: We included randomised controlled trials (RCTs) and controlled clinical trials (CCTs) that used quasi-randomised methods to allocate participants, investigating participants with rotator cuff disease with or without calcific deposits. We included trials of comparisons of extracorporeal or radial shock wave therapy versus any other intervention. Major outcomes were pain relief greater than 30%, mean pain score, function, patient-reported global assessment of treatment success, quality of life, number of participants experiencing adverse events and number of withdrawals due to adverse events. DATA COLLECTION AND ANALYSIS: Two review authors independently selected studies for inclusion, extracted data and assessed the certainty of evidence using GRADE. The primary comparison was shock wave therapy compared to placebo. MAIN RESULTS: Thirty-two trials (2281 participants) met our inclusion criteria. Most trials (25) included participants with rotator cuff disease and calcific deposits, five trials included participants with rotator cuff disease and no calcific deposits, and two trials included a mixed population of participants with and without calcific deposits. Twelve trials compared shock wave therapy to placebo, 11 trials compared high-dose shock wave therapy (0.2 mJ/mm² to 0.4 mJ/mm² and above) to low-dose shock wave therapy. Single trials compared shock wave therapy to ultrasound-guided glucocorticoid needling, ultrasound-guided hyaluronic acid injection, transcutaneous electric nerve stimulation (TENS), no treatment or exercise; dual session shock wave therapy to single session therapy; and different delivery methods of shock wave therapy. Our main comparison was shock wave therapy versus placebo and results are reported for the 3 month follow up. All trials were susceptible to bias; including selection (74%), performance (62%), detection (62%), and selective reporting (45%) biases. No trial measured participant-reported pain relief of 30%. However, in one trial (74 participants), at 3 months follow up, 14/34 participants reported pain relief of 50% or greater with shock wave therapy compared with 15/40 with placebo (risk ratio (RR) 1.10, 95% confidence interval (CI) 0.62 to 1.94); low-quality evidence (downgraded for bias and imprecision). Mean pain (0 to 10 scale, higher scores indicate more pain) was 3.02 points in the placebo group and 0.78 points better (0.17 better to 1.4 better; clinically important change was 1.5 points) with shock wave therapy (9 trials, 608 participants), moderate-quality evidence (downgraded for bias). Mean function (scale 0 to 100, higher scores indicate better function) was 66 points with placebo and 7.9 points better (1.6 better to 14 better, clinically important difference 10 points) with shock wave therapy (9 trials, 612 participants), moderate-quality evidence (downgraded for bias). Participant-reported success was reported by 58/150 people in shock wave therapy group compared with 35/137 people in placebo group (RR 1.59, 95% CI 0.87 to 2.91; 6 trials, 287 participants), low-quality evidence (downgraded for bias and imprecision). None of the trials measured quality of life. Withdrawal rate or adverse event rates may not differ between extracorporeal shock wave therapy and placebo, but we are uncertain due to the small number of events. There were 11/34 withdrawals in the extracorporeal shock wave therapy group compared with 13/40 withdrawals in the placebo group (RR 0.75, 95% CI 0.43 to 1.31; 7 trials, 581 participants) low-quality evidence (downgraded for bias and imprecision); and 41/156 adverse events with extracorporeal shock wave therapy compared with 10/139 adverse events in the placebo group (RR 3.61, 95% CI 2.00 to 6.52; 5 trials, 295 participants) low-quality evidence (downgraded for bias and imprecision). Subgroup analyses indicated that there were no between-group differences in pain and function outcomes in participants who did or did not have calcific deposits in the rotator cuff. AUTHORS' CONCLUSIONS: Based upon the currently available low- to moderate-certainty evidence, there were very few clinically important benefits of shock wave therapy, and uncertainty regarding its safety. Wide clinical diversity and varying treatment protocols means that we do not know whether or not some trials tested subtherapeutic doses, possibly underestimating any potential benefits. Further trials of extracorporeal shock wave therapy for rotator cuff disease should be based upon a strong rationale and consideration of whether or not they would alter the conclusions of this review. A standard dose and treatment protocol should be decided upon before further research is conducted. Development of a core set of outcomes for trials of rotator cuff disease and other shoulder disorders would also facilitate our ability to synthesise the evidence.