Biologic therapy has increasingly been used in the treatment of chronic diseases. Tumor necrosis factor (TNF) is a cytokine implicated in the pathogenesis of rheumatoid arthritis and inflammatory bowel disease. Anti-TNF therapy is being used in the treatment of these conditions. Since the introduction of anti-TNF agents, there have been many case reports of development of malignancy after the initiation of anti-TNF therapy. With increasing case reports, there is growing concern that anti-TNF therapy, albeit useful in the treatment of these chronic conditions, might be associated with the development of malignancy in patients. In this review we examine the different anti-TNF agents and different studies to evaluate any possible association between use of any anti-TNF agent and development of malignancy.