Nurse anesthetists are most common in the US, and most of the evidence on nurse anesthetists has been gathered there. In the US, the role of nurse anesthetists is outlined in government regulations and in the guidelines of the relevant associations. In Canada, with the exception of Quebec, the role of anesthesia assistants has developed informally. There are few published studies on the use of non-physicians in anesthesia care in Canada. Regarding the quality of anesthesia delivery by non-physicians, two US studies showed that there was no association between mortality rates and closed claims with the type of anesthesia provider. A forthcoming UK systematic review will provide a basis for further investigation of these topics.