Inflammatory bowel disease (IBD) is a chronic inflammatory disorder, which includes Crohn’s disease (CD) and ulcerative colitis (UC). The aim of therapy is to induce sustained remission, a state of long lasting quiescent disease. Several drugs exist to induce and maintain remission, and these drugs are usually prescribed in a step up fashion. In contrast to UC, for patients with CD after induction of remission with corticosteroids, maintenance of remission is only achieved with immunosuppressive drugs, mainly thiopurines. Although these drugs are effective in 60 % for remaining clinical remission after 12 months, the drawback of these drugs are the side effects that include bone marrow suppression, liver test abnormalities and malignancies. If conventional therapy fails, the next step in the treatment of CD is the introduction of biologics such as anti-TNF alpha inhibitors (anti-TNFa), vedolizumab and ustekinumab. While being a MOR antagonist, which blocks endogenous opioid effects when used at high concentrations, administration of low dose Naltrexone (LDN) is postulated to result in upregulation of endogenous encephalin and endorphin levels and have a positive modulatory effect on the MOR. Thus, the use of LDN in clinical settings is gaining interest, with CD, Multiple Sclerosis and fibromyalgia described as potential targets for treatment with LDN.The proposed study will be a 12-week, multicenter, randomized, placebo-controlled study, in 112 patients with mild to moderate active CD failing conventional treatment or having side effects to conventional treatment. The study is designed to assess the efficacy of LDN for the induction of endoscopic remission in mild to moderate CD.