The purposes of this study was to provide a retrospective comparison of semiquantitatively measured bowel wall vascularity by power Doppler sonography, endoscopic-histopathological biopsy findings, and disease activity in patients with confirmed Crohn's disease. Thirty-two out of 1,332 patients with histologically confirmed Crohn's disease (18 female, 14 male; mean age 38.8 years) met the inclusion criteria: ileocolonoscopy with biopsy and power Doppler sonographic determination of bowel wall vascularity with assessment of disease activity within a period of 5 days. Sonographic determination of bowel wall vascularity was based on a semiquantitative score. Endoscopic bowel wall biopsy specimens were assessed using a self-developed inflammation score and the disease activity was calculated using Crohn's disease activity index (CDAI). A significant association (p < 0.05) was shown for results of histology and bowel wall vascularity in the terminal ileum (kappa = 0.66; sensitivity 95%; specificity 69%). There was no observed association between CDAI and histology, although there was an association between CDAI and bowel wall vascularity (sensitivity 82%). Increased bowel wall vascularity in the terminal ileum measured by power Doppler ultrasound reflects inflammatory activity in histologically examined bowel wall. Power Doppler ultrasound may be able to monitor activity changes of the bowel wall determined by pharmaceutical treatment.