AbstractThe cubital tunnel is the most common site of ulnar nerve entrapment. Previous ultrasound studies have demonstrated enlargement of the ulnar nerve in cubital tunnel syndrome but did not report on the cubital tunnel itself. Twenty‐two individuals with cubital tunnel syndrome were evaluated with nerve conduction studies and ultrasound. The ultrasound measurement that most strongly correlated with conduction velocity was the ratio of ulnar nerve to cubital tunnel cross‐sectional area with the elbow flexed. Measurement of this ratio may improve the diagnostic accuracy of ultrasound in cubital tunnel syndrome, although further investigation is needed. Muscle Nerve, 2007