A randomized, double-blind, placebo-controlled trial has investigated whether the combination of adalimumab and ciprofloxacin is more effective than adalimumab alone in perianal fistulizing Crohn's disease. 76 patients from eight Dutch hospitals were included in the trial, which lasted 12 weeks. The primary end point (a 50% reduction in fistulas from baseline to week 12) was achieved in 71% of patients who received combination therapy and in 47% of patients receiving adalimumab plus placebo (P = 0.047).