Crohn's disease (CD) is a lifelong condition of inflammation in the bowel. CD can affect any part of the gastrointestinal tract from mouth to anus. Symptoms can include: tiredness, stomach pain, diarrhea (which may be bloody if the disease is severe), fever, weight loss, skin rashes, arthritis and inflammation of the eye.||Infliximab-IFX (Remicade®) is a medication that is used to treat CD in adults and children. In adults it has been shown that the amount of this drug a person has in their blood can show how well it is working for them. Health Canada has approved Infliximab -IFX for the treatment of CD in children 9 and older. In Canada, doctors may prescribe Inflixmab to younger children when other therapies do not resolve their disease symptoms. This is called "off-label" use of Infliximab.||IFX levels in the body and consequently its efficacy can be influenced by many biological characteristics within the patient's body. In about 17% of those treated with IFX, the patient's immune response against IFX may lead to a three to fivefold increased risk of loss of response. This immune response to the medication often occurs when drug levels are undetectable in the body. Thus it is in order to achieve best results with this treatment, physicians need to be able to adjust dosing specific to each patient. A recent study has shown that 29% of children have an undetectable IFX level at the 4th medication infusion. Up to 40% of patients receiving scheduled IFX have undetectable drug level prior to their next infusion.||In order to minimize the loss of response, we hope to conduct an observational cohort study of pediatric patients treated with IFX.||This open label, cohort study aims to:||Determine the pharmacokinetics of IFX in children with CD and the factors that affect IFX levels during the first three loading infusions|Obtain data to create a model that can guide and adjust the IFX dose and frequency to achieve optimal trough level between 5 and 10 ug /ml at 14 weeks.