The author presents a thorough review of bacterial interference and the studies that have been conducted in common ENT conditions. The simple concept is that a strong population of normal flora will interfere with colonisation and subsequent infection by pathogenic strains. By replacing or preserving this flora, the recurrence of infections can be reduced: alpha haemolytic streptococci have been successfully inoculated into the naso / oropharynx of children to reduce the recurrence of with Group A beta haemolytic streptococcal tonsillitis. Several randomised double-blind, placebo-controlled trials are presented to support this as an effective therapy. The role of selecting antibiotics to preserve normal flora (such as first or second generation cephalosporins) is presented, again with compelling evidence that a change in antibiotic prescribing away from penicillin might be a good thing. Bacterial interference appears to provide us with a new way to reduce the swelling tide of antibiotic resistance and is clearly worthy of further study.