Cat's claw (Uncaria tomentosa and Uncaria guianesis) is a medicinal plant from the Amazon commonly used to treat disorders such as arthritis, gastritis and osteoarthritis. The mechanism of cat's claw appears to be as an inhibitor of TNFalpha and antioxidant. Understanding the processes in osteoarthritis may facilitate and clarify the potential role of cat's claw as a complementary therapy to assist in the reduction of pro-inflammatory mediators and effectors. The clinical relevance of this therapy as a viable modality of intervention will be discussed.