Polymyalgia rheumatica is a clinical syndrome of proximal muscle pain in older patients that often presents a diagnostic challenge because of the large differential diagnosis, lack of definitive diagnostic criteria, and relatively frequent "atypical" clinical findings, such as peripheral synovitis, distal extremity pain, normal erythrocyte sedimentation rate, and mild weakness. Despite an extensive differential diagnosis that includes endocarditis and steroid-responsive malignant neoplasms, routine laboratory testing should be limited, and a low-dose corticosteroid trial is useful as the final step in the evaluation. The clinical overlap with seronegative rheumatoid arthritis is striking, suggesting that these diagnoses may represent different presentations of a similar disease process. While concurrent asymptomatic temporal arteritis is common, there are no data to support obtaining a temporal artery biopsy in patients with pure polymyalgia rheumatica symptoms.