Cervical spondylotic myelopathy (CSM) is the chronic and slow deterioration of cervical spinal cord function. The pathophysiology of this condition is multifactorial, including compression, repetitive trauma, and vascular compromise of the spinal cord. Clinically, it presents as a progressive decline in patients' appendicular neurological function. The natural history of this disease varies but, it is well-known that the duration and degree of compression correlate negatively with prognosis. A mild degree of CSM tends to stabilize with potential improvement over time while more severe CSM tends to progress. Surgical intervention has shown to positively alter the natural history of the disease by halting the progression with some restoration of function. Ossification of the posterior longitudinal ligament (OPLL) is a chronic disease that results in progressive ossification of the posterior longitudinal ligament of the spine. It commonly affects the cervical spine. The etiology is multifactorial in nature, including genetic and environmental factors. The progressive nature of this condition and the resultant cervical spinal stenosis make it one of the main causes of cervical myelopathy (CM). There is no medical therapy for this disease, and surgery is reserved for patients with CM caused by spinal cord compression. In this article, we review the different aspects of the natural history of both CSM and OPLL.