Tumor necrosis factor (TNF) alpha is a major proinflammatory cytokine involved in the immune response in inflammatory bowel disease (IBD). Anti-TNF drugs such as infliximab and adalimumab are used to treat IBD; however, approximately 30% of patients do not respond to treatment. Individual genetic differences could contribute to lack of efficacy. Genetic studies have tried to uncover the factors underlying differences in response, however, knowledge remains limited, and the results obtained should be validated, so that pharmacogenetic information can be applied in clinical practice. In this review, we gather current knowledge in the pharmacogenetics of anti-TNF drugs in patients with IBD. We observed a connection between the major genes described as possible predictors of response to anti-TNF drugs in IBD and the cytokines and molecules involved in the T helper (Th) 17 pathway. Full article