A multi-country outbreak of Mycobacterium chimaera infection associated with contaminated heater-cooler devices (HCDs) has been reported, with more than 70 cases in Europe and the United States and two cases in Canada to date. The epidemiological and microbiological characteristics of this outbreak provide evidence for common-source transmission of M. chimaera from the exhaust air of intrinsically contaminated HCDs to patients during cardiac surgery. To date, all reported cases have been associated with Stöckert 3T HCDs manufactured at one plant by LivaNova prior to September 2014. Implantation of prosthetic material increases the risk of infection. Infections usually present as prosthetic valve endocarditis, vascular graft infection or disseminated infection. Reported mortality rates have varied, but were often over 40%. Several measures are recommended to facilitate case-finding and mitigate risk of exposure. The feasibility of some risk mitigation measures and their effectiveness in reducing the risk of exposure are yet to be determined. Until HCDs are redesigned in a manner that prevents water contamination and aerosolization, separating the HCD exhaust air from the operating room air during surgery may be the most effective risk mitigation strategy. However, possible unintended consequences of this approach should be considered. This overview summarizes findings from peer-reviewed and other relevant national documents on key features of the outbreak, including the source, identified risk factors for infection, signs and symptoms of infection, burden of disease, risk mitigation measures, management challenges and knowledge gaps.