Genetically modified (GM) crops are grown on 6 million hectares annually in Canada; with 80 percent of this area being GM canola (Brassica napus L.).  Despite their rapid adoption over the last decade, and the significant potential benefits that may be realized in the future, much controversy surrounds GM crops.  One of the biggest and most difficult issues to evaluate is the potential effects of GM crops on the environment.  This paper outlines several studies that deal with the potential environmental impacts of GM crop production in Canada.