This study assessed the sensitivity of four different types of one-legged hop tests. The goal was to determine alterations in lower limb function in ACL deficient knees. Regression analyses were conducted between limb symmetry as measured by the hop tests and muscle strength, symptoms, and self-assessed function. In 67 patients, 50% had abnormal limb symmetry scores on a single hop test. When the results of two hop tests were calculated, the percent of abnormal scores increased to 62%. The percentage of normal scores indicated that these hop tests had a low sensitivity rate. However, the high specificity and low false-positive rates allow the tests to be used to confirm suspected defects in lower limb function. Statistical trends were noted between abnormal limb symmetry on the hop tests and low velocity quadriceps isokinetic test results.