Background and Aims The role of E.coli in Crohn[symbol]¯s disease pathogenesis is uncertain. This Phase 2a study aimed to assess efficacy and safety of an antibiotic/hydroxychloroquine combination effective against E.coli inside macrophages. Methods Adults with active disease (CDAI>220 plus CRP¡Ý5mg/l and/or faecal calprotectin >250 ug/g) were randomised to receive (open label) oral budesonide (Entocort CR 9mg/day 8 weeks, 6mg/day 2 weeks, 3mg/day 2 weeks) or oral ciprofloxacin 500mg bd, doxycycline 100mg bd, hydroxychloroquine 200 mgs tds for 4 weeks, followed by doxycycline 100 mg bd and hydroxychloroquine 200mgs tds for 20 weeks. Use of anti-TNF in the previous 3 months was excluded. Primary endpoints were remission (CDAI