The purpose of this study was to examine longitudinally the natural history of asymptomatic rotator cuff tears over a 5-year period and to assess the risk for development of symptoms and tear progression. Since 1985 through the present, bilateral sonograms were done on all patients. A review of consecutive sonograms done from 1989 to 1994 revealed 58 potential patients with unilateral symptoms who had contralateral asymptomatic rotator cuff tears. Of these 58 patients, 45 (22 men, 23 women) responded to a comprehensive questionnaire and 23 additionally returned for examination and repeat sonographic evaluation. The questionnaire was based on the American Shoulder and Elbow Surgeons score and included several outcome-based questions. A physical examination was performed in a standardized fashion along American Shoulder and Elbow Surgeons guidelines. Repeat high-resolution sonograms were performed by a single experienced radiologist. Primary and repeat sonograms were then reassessed for tear size and location by two independent experienced radiologists blinded to the clinical data results. Twenty-three (51%) of the previously asymptomatic patients became symptomatic over a mean of 2.8 years. The average Activities of Daily Living score for those remaining asymptomatic was 28.5 of 30 and for those becoming newly symptomatic, 22.9 of 30 (P <.5). The mean visual analog pain score (1 = no pain) for those remaining asymptomatic was 1.1 and for the newly symptomatic patients, 4.0. Of the 23 patients who returned for ultrasound, 9 were asymptomatic and 14 symptomatic. Only 2 of the 9 patients remaining asymptomatic had progression of their tears. Overall, 9 of 23 patients had tear progression. No patient had a decrease in the size of the tear. Our results demonstrate that symptoms can develop in patients with previously asymptomatic rotator cuff tears when seen in the context of a contralateral symptomatic tear. Development of symptoms was associated with a significant increase in pain and decrease in the ability to perform activities of daily living (P <.05). There appears to be a risk for tear size progression over time.