Abstract: OBJECTIVE To determine whether sulphasalazine plus prednisone is more effective than sulphasalazine alone in treating active Crohn disease. DESIGN Randomized, double-blind, placebo-controlled trial. SETTING Multicenter trial in one university hospital and nine general hospitals. PATIENTS Patients with active Crohn disease and a Van Hees Activity Index of 140 or more. Of 71 patients who were randomly assigned, 60 completed treatment and were analyzed. INTERVENTIONS For 16 weeks, 30 patients received sulphasalazine, 6 g/d (or 4 g/d if adverse effects occurred) and prednisone, 30 mg/d initially. Prednisone therapy was tapered in increments of 5 mg/2 wk to 10 mg/d after 8 weeks. Thirty other patients received sulphasalazine and a placebo. MEASUREMENTS AND MAIN RESULTS In the first 6 weeks of treatment, the Van Hees Activity Index decreased to a median of 70% (interquartile range, 57% to 81%) of the initial value in patients treated with sulphasalazine and prednisone and to a median of 87% (interquartile range, 70% to 94%) in patients treated with sulphasalazine alone (P = 0.001). In the last 4 weeks of treatment, the corresponding figures were 63% (interquartile range, 40% to 75%) and 70% (interquartile range, 54% to 90%) (P = 0.10). The Crohn's Disease Activity Index decreased in the first 6 weeks to a median of 65% (interquartile range, 57% to 86%) in patients receiving sulphasalazine and prednisone and to a median of 75% (interquartile range, 58% to 101%) in patients receiving sulphasalazine alone (P = 0.13). In the last 4 weeks of treatment, the corresponding figures were 65% (interquartile range, 42% to 90%) and 76% (interquartile range, 49% to 110%) (P = 0.19). CONCLUSIONS The use of prednisone in addition to sulphasalazine in patients with active Crohn disease results in a significantly faster initial improvement, but not in a significantly better result after 16 weeks of treatment, when disease activity is measured by the Van Hees Activity Index.