We used data from the 1991-2006 Canadian Census Mortality and Cancer Follow-up Study to compare all-cause mortality for immigrants with that of the Canadian-born population. The study addressed two related questions. First, do immigrants have a mortality advantage over the Canadian-born? Second, if immigrants have a mortality advantage, does it persist as their duration of residence increases? The analysis fitted sex-stratified hazard regression models for the overall sample and for selected countries of birth (UK, China, India, Philippines, and the Caribbean). Predictors were assessed at baseline. Mortality was lower among immigrants than the Canadian-born even after adjusting for a selected group of socio-demographic and socio-economic factors. The mortality differences persisted even after long residence in Canada, but appeared to be dependent on the age of the individual and the country of origin. Interpreted in light of known explanations of immigrant mortality advantage, the results mostly reflect selection effects.