Outcome measurement in sports physiotherapy is directed at identifying an athlete's ability to tolerate the physical demands inherent in sport-specific activity and prevent re-injury on return-to-competition. Outcome measures currently utilized following anterior cruciate ligament (ACL) injury include clinical, functional performance test (FPT), and subjective measures. The FPT simulates the forces encountered during sport-specific activity under controlled clinical conditions, the use of the FPT increasing since traditional clinical outcome measures, such as knee joint laxity and isokinetic quadriceps muscle strength, demonstrate weak to moderate and often insignificant relationships with functional tasks. Many FPTs, such as hop, leap, jump, sprint, and agility FPTs, may be administered to an athlete following knee ligament injury. However, when selecting a FPT for the assessment of knee function, the clinician must acknowledge issues relating to reliability, validity, data analysis, and at what point in the rehabilitation process a FPT should be administered if the data generated are to be meaningful and useful. Therefore, the purpose of this paper is to present a comprehensive and detailed review of the FPT literature in order to assist the sports physiotherapist with the clinical application of a FPT to an athlete following knee ligament injury.