Our aims were to assess the impact on health-related quality of life (HRQOL) of a controlled ileal release (CIR) formulation of budesonide in active Crohn's disease (CD) and further define the role of HRQOL, using the Inflammatory Bowel Disease Questionnaire (IBDQ), in assessing outcome in CD. A randomized trial was conducted in 258 patients with active ileal or ileocecal CD. Budesonide CIR 1.5 mg, 4.5 mg, 7.5 mg, or placebo was given b.i.d. for 8 weeks. IBDQ score changes were compared among groups. Correlations for IBDQ and Crohn's Disease Activity Index (CDAI) scores were calculated. Mean IBDQ scores improved significantly over placebo by 2 weeks in budesonide 15 mg (155+/-38; p = 0.006) and 9 mg groups (157+/-33; p = 0.0002). Bowel, systemic, social, and emotional subscores were also significantly better (p < 0.002) at 2 and 8 weeks in the 9 mg group. Improved HRQOL scores correlated well with decreased CDAI (-0.8 < r < -0.4). Average per item change in IBDQ at remission was 1.17 to 1.48. Prior surgery (p < 0.005) or current smoker (p < 0.05) status predicted poorer initial HRQOL but not response. Budesonide CIR 9 or 15 mg/day rapidly and significantly improved HRQOL in active CD.