Germinated barley foodstuff (GBF) is a prebiotic which increases luminal butyrate production by modulating the microfloral distribution. GBF has been shown to reduce both clinical activity and mucosal damage in active ulcerative colitis (UC) with mild to moderate activity. However, the efficacy of GBF in patients with UC during the remission stage is unknown. The aim of this study was to investigate the efficacy of GBF as a maintenance therapy in patients with UC while in remission. Fifty-nine patients with UC in remission according to Rachmilewitz's clinical activity index (CAI) score of </=4 were enrolled and divided into two groups, control (n=37) and GBF (n=22). Patients in the control group were given conventional treatment alone for 12 months, while patients in the GBF group received conventional therapy plus 20 g of GBF daily. The response to treatments was assessed by monitoring the CAI and endoscopic score according to Matts. Significantly better CAI values were seen in the GBF group at 3, 6, and 12 months compared with the values in the control group. The cumulative recurrence rate in the GBF group with steroid tapering treatment was significantly lower compared with the value in the control group. No side effects related to GBF were observed. GBF appeared to be effective and safe as a maintenance therapy to taper steroid dose and prolong remission in patients with UC.