Psoriatic arthritis is an inflammatory arthropathy associated with psoriasis and characterized by absence of rheumatoid factor. Any form of psoriasis can be complicated by joint inflammation. Four groups have been identified: pauciarticular psoriatic arthritis, psoriatic spondylitis, symmetrical polyarticular psoriatic arthritis and arthritis mutilans. The etiology of psoriatic arthritis remains unclear. Genetic, immunologic and environmental factors are thought to be important in the development of the disease. The role of cytokines and adhesion molecules in the mechanism of joint destruction is highlighted, and recent therapeutic strategies are discussed.