Emerging infections may be defined as infectious diseases whose incidence in humans has increased in the past 2 decades or threatens to increase in the near future. They include: new infections resulting from changes or evolution of existing organisms; known infections spreading to new geographic areas or populations; previously unrecognised infections appearing in areas undergoing ecological transformation; and old infections re-emerging as a result of antimicrobial resistance in known agents. Emerging infections occur as the result of four groups of factors: novel zoonotic emergence factors; climate change; non-zoonotic emergence factors; and human practices. As frontline doctors, family physicians have at least five roles that they must perform well: participate in global and local surveillance of emerging infections; assist in societal learning; pandemic preparedness; legislation compliance; and antibiotic stewardship.