Spaghetti meat (SM) is a recently recognized myopathy that occurs in the Pectoralis major of modern fast-growing broilers. The SM abnormality is characterized by loss of muscle structural integrity and loosely separated muscle fibers and bundles. This condition causes significant economic losses to the industry due to the affected breast meat being downgraded. There is a growing body of research on various aspects of SM; however, the specific cause for SM is not fully understood. This chapter seeks to provide an overview of what is currently known about the SM myopathy and describes the influence of the SM myopathy on breast meat composition and quality traits as well as potential pathological mechanisms and predisposing factors for the myopathy.