In briefChronic pain following an ankle sprain is disabling for the active patient and a diagnostic challenge for the physician. With a differential diagnosis in mind and the relative benefits of imaging procedures in hand, the primary care physician can expediently come to a definitive diagnosis in most instances. Incomplete rehabilitation is most often the cause of chronic pain following an ankle sprain. The differential diagnosis also includes lateral ankle instability, previously undetected trauma, impingement disorder, congenital abnormality, and tumor.