Ulnar neuropathy at the elbow is a common entrapment mononeuropathy. Leaning the elbow on hard floors for a long time, frequent and strong elbow movements, and chronic diseases such as diabetes mellitus may be the risk factors for ulnar neuropathy. Patients often present with sensory abnormalities in the fourth/fifth finger and weakness in the hand muscles innervated by the ulnar nerve. The disease can be mild or cause severe weakness that limits daily activities. Therefore, diagnosis, treatment, and follow-up of patients are important. The diagnosis of ulnar neuropathy can be made by clinical features, electrodiagnostic tests, and imaging methods. Since chronic diseases such as diabetes mellitus and thyroid disease can be seen together with ulnar neuropathy, biochemical tests including blood glucose and thyroid tests should be applied to patients. Treatment of ulnar neuropathy includes medical, physical therapy practices, and surgery.