Heavy oil waterfloods have been operated in Saskatchewan and Alberta for up to 50 years, yet remarkably little discussion of the theory or operation of heavy oil waterflooding has been published. Conventional waterflood theory is based on assumptions that are not encountered in heavy oil reservoirs, and those theoretical and operational experiences should not be substituted. This editorial draws upon information from the relatively small Canadian heavy oil waterflooding available in the public domain to establish that the "state of the art," including proposed production mechanisms, prediction of performance, and improvement of performance, is extremely limited.