Tendonitis, tenosynovitis, and the arthritides are clinical problems commonly encountered in daily orthopaedic practice. Systemic anti-inflammatories, physical therapy, and local corticosteroid injections all are used as nonoperative treatments of these conditions. Systemic anti-inflammatory agents and local corticosteroid agents, however, can be associated with adverse effects that render them intolerable to some patients. As a preliminary study assessing the feasibility of local injection of nonsteroidal anti-inflammatory medication, the histological and biomechanical effects of local exposure of rabbit cartilage and tendon to injectable steroidal (corticosteroid) and injectable nonsteroidal anti-inflammatory agents (ketorolac tromethamine, KT) were determined. Thirty rabbits underwent bilateral knee joint, patellar tendon, and Achilles tendon injections with either normal saline, corticosteroid, or KT. Mechanical and histologic evaluation of the tissues was performed at 6 and 15 weeks after injection. Gross tendon adhesions were observed in more corticosteroid-treated specimens than those exposed to normal saline or KT. Microscopic evaluation of tendons revealed no significant differences among the three groups. Mild cartilage degenerative changes were noted across all groups. Evidence of cartilage necrosis was noted for the corticosteroid-treated group only. Tendons exposed to corticosteroid or KT demonstrated increased load and energy to failure, but exhibited no difference in material stiffness or strain. The use of an injectable nonsteroidal anti-inflammatory agent may be safe and even pose less threat to local tissues after intra-articular and peri-tendinous administration.