There is an acute need for the development of effective therapies for mucositis, a debilitating side effect of cancer chemotherapy. Iberogast is a herbal extract reported to possess anti-inflammatory properties. We investigated Iberogast for its potential to reduce the severity of 5-Fluorouracil (FU)-induced mucositis in rats. Rats were allocated to three treatment groups (n = 8) and gavaged daily with a 10% solution of Iberogast or water from day 0 to day 8. Rats were injected intraperitoneally with 5-FU (150 mg/kg) or saline on day 6, and killed after 72 h. In vivo and in vitro sucrase activity was assessed by (13)C-sucrose breath test (SBT) and sucrase assay respectively. Intestinal disease severity was determined by histological assessment of villus height and crypt depth. Significant increases in villus height (277 +/- 9 microm) and crypt depth (67 +/- 3 microm) were observed in 5-FU + Iberogast-treated rats compared with 5-FU + Water (224 +/- 13 microm and 48 +/- 2 microm respectively; p < 0.05). Sucrase activity was significantly reduced in all 5-FU groups compared to control. Significant reductions in SBT and sucrase activity were observed in all 5-FU groups compared with Saline + Water controls (p < 0.05). We conclude that although Iberogast partially improved the histopathological features of 5-FU induced mucositis, it conferred no significant protection as indicated by the assessed endpoints.