A standardized grading scheme for the assessment of acute cellular rejection (ACR) in small-intestine transplantation was proposed in 2003 at the Eighth International Small Intestinal Transplantation Symposium. We have implemented the current grading scheme for ACR in small-bowel transplantation since October 2003. The pathologic diagnoses of those small-intestine biopsy samples, including ACR grade and other supplementary findings were evaluated. A total of 3484 small intestine biopsy samples from 155 patients were available for evaluation in this study. Frequency of grades 0, indeterminate, 1, 2, and 3 acute cellular rejection was 33.9%, 49.1%, 12.6%, 3.7%, and 0.8%, respectively. Duration of ACR episode strongly correlated with grade of ACR episode (P < .001). Other supplementary findings included acute vascular rejection component, 2.2%; increase in lymphoplasmacytic infiltrate in lamina propria, 15.7%; mucosal fibrosis, 0.4%; and regenerative changes, 0.3%. Our data substantiate that this grading system is reliable and useful for clinical decision making in bowel transplantation. We suggest that an assessment and quantification of supplementary findings be considered a component of the International Pathology Grading Scheme.