In July 2000, the province of Ontario, Canada, initiated a universal influenza immunization program to provide free seasonal influenza vaccines for the entire population, the first large-scale program of its kind worldwide. This document reviews an economic appraisal of the program, comparing it to a targeted influenza immunization program, and concluding that universal immunization is estimated to be an economically attractive intervention. The study was supported by an operating grant from the University of Toronto Research Program.