The aim of this study was to evaluate the epidemiologic data of patients with an acute soft-tissue injury to the shoulder, with an emphasis on improving the early diagnosis of acute rotator cuff tears. This study included 104 patients, with a median age of 49 years (range, 19-75 years). The patients were evaluated clinically and with ultrasonography at a median of 13 days (range, 3-49 days) after the injury. A total of 60 patients (58%) had some degree of cuff lesion on the ultrasonographic examination. Of these patients, 33 (32%) had a full-thickness rotator cuff tear, 14 (13%) had a partial-thickness cuff tear in the tendon substance, and 13 (13%) had a partial cuff tear at the insertion site on the major tubercle. The injury mechanism or activity at the moment of injury did not correlate with the presence of a rotator cuff lesion, but we found a strong age correlation, with a prevalence of any rotator cuff tear, above 50%, for patients aged above 50 years and with a prevalence of full-thickness tears of 50% in the groups aged 50 to 59 years and aged 60 to 69 years. In conclusion, this study found a high incidence of rotator cuff lesions by further evaluation of patients undergoing consultation at the emergency department, with an inability to perform active abduction above 90 degrees and normal radiographs, after an acute shoulder trauma.