The importance of acromial morphology in the pathogenesis of rotator cuff tears remains controversial. Some surgeons place great emphasis on acromial morphology and others feel that acromial shape is a result of cuff tear pathology rather than the cause. The purpose of this study was to determine if there was an association between acromial morphology, age, and rotator cuff tears found by ultrasound in asymptomatic volunteer subjects with no past history of shoulder symptoms. One hundred eighteen outlet x-rays and ultrasound scans were performed in 59 asymptomatic patients in various age groups. Acromial morphology and the age of the patients were then correlated with the ultrasound findings. Older patients were noted to have a high incidence of type II and type III acromions (93% of those over 70). Full- and partial-thickness tears were more commonly seen in patients with type II or type III acromions compared with type I. Patients over 50 years had a high incidence of full-thickness tears (40%), but the incidence did not increase with increasing age past 50. These findings lend credence to the multifactorial etiology of rotator cuff tears. The patient's age (degeneration) and acromial morphology (impingement) are two of the factors involved in causing rotator cuff tears. The incidence of cuff tears and type III acromions was high in this group of entirely asymptomatic volunteer subjects. Surgeons should interpret radiologically hooked or curved acromions as well as rotator cuff tears diagnosed with ultrasound or other modalities with caution. It may well be that both of these findings should be regarded as part of the natural ageing process.