The clinical management of Crohn's disease can be considered in relation to the treatment of acute disease and the maintenance of remission. The medication used to achieve these two goals may or may not be the same. Some patients with mildly active disease may respond to high-dose (4 g/day) mesalazine (mesalamine), and 5-aminosalicylic acid may also be helpful in weaning a patient off steroids after treatment for a flare-up. However, the value of 5-aminosalicylic acid in maintaining remission in Crohn's disease remains controversial. Subgroups of patients may be helped: for example, patients with Crohn's disease who have experienced a relapse within the last 2 years may benefit. Steroids form the first-line therapy for acute episodes of inflammation but do not maintain remission. Azathioprine and mercaptopurine are the first-line drugs for the maintenance of remission in moderate to severe Crohn's disease, and by titrating the dose up from 2 mg/kg daily, some previously resistant patients will be brought into remission. One-half of patients who do not tolerate azathioprine will tolerate mercaptopurine. Methotrexate is effective in inducing and maintaining remission, and is useful for patients who fail azathioprine treatment. Thalidomide is not proven in controlled studies, but two open studies have demonstrated its efficacy. The optimal dose, however, remains to be defined. Purified liquid diets with food exclusion can induce remission in patients with active disease, but food exclusion is difficult to maintain long term. Infliximab can induce and maintain remission in patients resistant to other therapies, with two-thirds of patients initially responding to treatment. One-third go into remission and, of those who respond to a single treatment, approximately one-half maintain remission when treated regularly for a year. Infliximab is, however, associated with an increased risk of infection, and its effect on cancer incidence is uncertain. The development of antibodies against the drug is associated with a loss of effect and allergic infusion reactions. In summary, simple proven therapies should be used first, because of their safety and benefit in some patients. However, aggressive therapy should be used when needed.