PURPOSE: The objective of this study was to assess the frequencies of ultrasound findings in patients with acute rotator cuff disorders in family medicine. METHODS: In a prospective observational study, 129 patients aged 18 to 65 years with acute shoulder pain in whom the family physician suspected rotator cuff disease underwent ultrasound imaging. RESULTS: Rotator cuff disease was present in 81% of the patients, and 50% of them had multiple disorders. Calcific tendonitis was the most frequently diagnosed specific disorder. An age of 40 years or older was most strongly related to rotator cuff disease. CONCLUSIONS: Ultrasound imaging enables family physicians to rationalize treatment in nearly all patients who are aged 40 years and older with acute shoulder pain.