Objective: To determine the diagnostic accuracy of commonly used physical tests for subacromial impingement syndrome, using ultrasound as the reference standard. Design: A cross-sectional study of 59 participants with chronic shoulder pain of more than four months duration with a referral for diagnostic ultrasound scanning were invited to participate in the study. Main measures: Thirty-four participants met the inclusion criteria and had an ultrasound scan followed immediately by application of the following tests: Neer's sign, Hawkins and Kennedy test, painful arc of abduction, empty and full can tests, resisted isometric shoulder abduction and resisted isometric shoulder external rotation. Using the two-way contingency table method sensitivity, specificity, likelihood ratios and overall accuracy were calculated for each physical test. Results: Diagnostic values for each test varied considerably. The Hawkins and Kennedy test was the most accurate test for diagnosing any degree of subacromial impingement syndrome (71.0%). The most accurate tests for diagnosing subcategories of impingement were pain on resisted external rotation and weakness during the full can test (63.6%) for presence of subdeltoid fluid, pain on resisted external rotation (58.8%) for partial thickness tears and the painful arc test (62.1%) for full thickness tears. Conclusions: As the predictive values of these tests are shown to be variable in this study it indicates that the clinical tests identified have limited use in informing diagnosis. Emphasis on the management of dysfunction may be more appropriate rather than reliance on clinical tests with inconclusive sensitivity and specificity if ultrasound scanning is not available.