A combination of infliximab and immunomodulators is the most efficacious treatment for Crohn’s disease (CD). Patients have the best outcomes when their serum concentrations of these drugs are above a determined therapeutic threshold. We performed a prospective, randomized trial to determine whether therapeutic drug monitoring (TDM) to maintain serum levels of infliximab above 3 μg/mL produced higher rates of clinical and endoscopic remission than adapting dose based only on symptoms.