Background The subacromial impingement syndrome (SIS) includes the rotator cuff syndrome, tendonitis and bursitis of the shoulder. Treatment includes surgical and non-surgical modalities. Non-surgical treatment is used to reduce pain, to decrease the subacromial inflammation, to heal the compromised rotator cuff and to restore satisfactory function of the shoulder. To select the most appropriate non-surgical intervention and to identify gaps in scientific knowledge, we explored the effectiveness of the interventions used, concentrating on the effectiveness of physiotherapy and manual therapy. Methods The Cochrane Library, PubMed, EMBASE, PEDro and CINAHL were searched for relevant systematic reviews and randomised clinical trials (RCTs). Two reviewers independently extracted data and assessed the methodological quality. A best-evidence synthesis was used to summarise the results. Results Two reviews and 10 RCTs were included. One RCT studied manual therapy as an add-on therapy to self-training. All other studies studied the effect of physiotherapy: effectiveness of exercise therapy, mobilisation as an add-on therapy to exercises, ultrasound, laser and pulsed electromagnetic field. Moderate evidence was found for the effectiveness of hyperthermia compared to exercise therapy or ultrasound in the short term. Hyperthermia and exercise therapy were more effective in comparison to controls or placebo in the short term (moderate evidence). For the effectiveness of hyperthermia, no midterm or long-term results were studied. In the midterm, exercise therapy gave the best results (moderate evidence) compared to placebo or controls. For other interventions, conflicting, limited or no evidence was found. Conclusions Some physiotherapeutic treatments seem to be promising (moderate evidence) to treat SIS, but more research is needed before firm conclusions can be drawn.