The glenohumeral joints of 32 patients (aged 60 or above) were examined using ultrasonography. Thirteen patients were suffering from characteristic polymyalgia rheumatica (PMR) symptoms. In contrast 19 other patients initially had similar complaints, but were diagnosed as having elderly onset rheumatoid arthritis (EORA) upon development of typical symptoms. Ultrasound examination revealed glenohumeral joint inflammation in 61% (8 out of 13) of the patients with PMR and 63.2% (12 out of 19) of the patients with EORA. These findings suggest that a subgroup of patients with PMR and EORA suffers from shoulder joint inflammation and this synovitis/bursitis/intraarticular effusion might play an important role in the understanding of their symptoms. We conclude that overlapping forms of PMR and a predominate rheumatoid factor negative subgroup of EORA might exist and should be further characterized.