US is indicated in the study of the impingement syndrome. A series of 152 shoulders was examined in a clinical-US study carried out following a standard protocol including a physical examination first and then a US examination. The study was aimed at investigating the agreement between clinical and US findings and at assessing the diagnostic reliability of US. 57% of the shoulders were positive to clinics (1 test at least) and were then divided in 4 groups. Positivity rate was high (85-87% for at least 3 or 4 tests). US findings included several different patterns. Our results demonstrate that a correct clinical-diagnostic protocol increases reliability, besides reducing the use of more complex and expensive imaging modalities--e.g., CT and MR.