Patellar ligament injuries are rare but may be seen in jumping horses. The middle patellar ligament is the most commonly affected. Lameness is variable but may be severe in acute cases. Clinical signs are often subtle; femoropatellar joint effusion, periligamentous thickening, and edema are inconsistent findings. In many horses, lameness is unchanged by intra-articular anesthesia of the femoropatellar joint; therefore, diagnosis is confirmed by ultrasonography. Treatment is prolonged rest (up to 6 mo). Lameness is often slow to resolve and may recur.