Tennis elbow is a common yet sometimes complex musculoskeletal condition affecting many patients treated by physical therapists. The purpose of this article is to review the anatomy, clinical examination, differential diagnosis, conservative care, and surgical treatment for tennis elbow or lateral epicondylitis. Particular attention is given to determining the precise pathological cause of lateral epicondylitis, with consideration of intrinsic and extrinsic factors associated with this condition. This information should assist health care practitioners who treat patients with this disorder.