AIM:To determine the efficacy and safety of rapid induction therapy with oral tacrolimus without a meal in steroid-refractory ulcerative colitis(UC)patients.METHODS:This was a prospective,multicenter,observational study.Between May 2010 and August 2012,49 steroid-refractory UC patients(55 flare-ups)were consecutively enrolled.All patients were treated with oral tacrolimus without a meal at an initial dose of 0.1mg/kg per day.The dose was adjusted to maintain trough whole-blood levels of 10-15 ng/m L for the first 2 wk.Induction of remission at 2 and 4 wk after tacrolimus treatment initiation was evaluated using Lichtiger’s clinical activity index(CAI).RESULTS:The mean CAI was 12.6±3.6 at onset.Within the first 7 d,93.5%of patients maintained high trough levels(10-15 ng/m L).The CAI significantly decreased beginning 2 d after treatment initiation.At 2wk,73.1%of patients experienced clinical responses.After tacrolimus initiation,31.4%and 75.6%of patients achieved clinical remission at 2 and 4 wk,respectively.Treatment was well tolerated.CONCLUSION:Rapid induction therapy with oral tacrolimus shortened the time to achievement of appropriate trough levels and demonstrated a high remission rate 28 d after treatment initiation.Rapid induction therapy with oral tacrolimus appears to be a useful therapy for the treatment of refractory UC. AIM: To determine the efficacy and safety of rapid induction therapy with oral tacrolimus without a meal in steroid-refractory ulcerative colitis (UC) patients. METHODS: This was a prospective, multicenter, observational study. Setween May 2010 and August 2012, 49 steroid -refractory UC patients (55 flare-ups) were consecutively enrolled. All patients were treated with oral tacrolimus without a meal at an initial dose of 0.1 mg / kg per day. The dose was adjusted to maintain trough whole-blood levels of 10- 15 ng / m L for the first 2 wk. Induction of remission at 2 and 4 wk after tacrolimus treatment initiation was evaluated using Lichtiger’s clinical activity index (CAI) .RESULTS: The mean CAI was 12.6 ± 3.6 at onset. Whithin the first 7 d, 93.5% of patients maintained high trough levels (10-15 ng / m L). The CAI decreased as early as 2 d after treatment initiation. At 2 wk, 73.1% of patients experienced clinical responses. After tacrolimus initiation, 31.4% and 75.6 % of patients achieved clinical remission at 2 and 4 wk, respectively. Treatment was well tolerated. CONCLUSION: Rapid induction therapy with oral tacrolimus shortened the time to achievement of appropriate trough levels and demonstrated a high remission rate of 28 d after treatment initiation. Rapid induction therapy with oral tacrolimus appeared to be a useful therapy for the treatment of refractory UC.