Crohn's disease (CD) is an incurable debilitating disorder affecting an increasing number of children. The etiology remains elusive, but a genetically determined aberrant immune response against microbiota appears to be responsible. TNFα plays a pivotal role in the cytokine cascade of the inflammatory process and mediates multiple processes central to the pathogenesis of CD. The natural history of pediatric CD is characterized by recurrent flare-ups that severely impair patients growth, pubertal development and nutritional status. Epidemiological observations have shown that the course of CD, despite conventional treatment, inevitably progresses to the development of severe complications and surgery. Infliximab is the most widely used biological agent in moderate-to-severe pediatric CD. At present biologics are used after the failure of conventional drugs (step-up approach) and represent the peak of the CD therapeutic pyramid. The early use of biologics (top-down approach) has been demonstrated to be effective in adults with CD. The project aims at evaluating if a top-down approach may achieve mucosal healing before irreversible tissue damage present in late CD and thus alter the natural course of the disease, compared to the conventional approach. The study can also add information about the safety of infliximab used as first-line therapy and may add data on the benefit and costs of a reversal of the traditional therapeutic pyramid in pediatric CD, guiding the clinician in deciding in whom, when and how to introduce early aggressive treatment in daily practice.