Flax (Linum usitatissimum L.) is being evaluated as a crop platform for the production of bio-industrial and nutraceutical products.  An important consideration for the release of any novel trait is the potential for gene flow to wild or weedy relatives and the impact it may have on their populations.  The potential for gene introgression from transgenic flax to wild relatives, the occurrence, the phylogeny of flax wild relatives and reported interspecific hybridization was reviewed to initiate the evaluation of environmental risk of novel flax in Canada.  The genus Linum contains approximately 230 species which are distributed in many parts of the world and may grow in sympatry with cultivated flax.  Interspecific hybridization and cytogenetic studies between flax and congeneric species demonstrated that cultivated flax has the ability to hybridize and form viable F1 plants with at least nine species of Linum (L. africanum, L. angustifolium, L. corymbiferum, L. decumbens, L. floccosum, L. hirsutum, L nervosum, L. pallescens, and L. tenue).  Hybridization of flax with many other wild relatives has either not been studied or reported.  However, based on the evidence of reported hybridization with wild or weedy relatives, gene flow from flax to wild or weedy relatives is possible in several species native to North America, depending on species distribution, sympatry, concurrent flowering, ploidy level, and sexual compatibility.