Gene flow is transfer of genetic information between populations of the same or different species. Gene flow in bread wheat (Triticum aestivum L.) occurs via pollen or seed dispersal. Under normal conditions, gene flow between wheat cultivars is negligible due to selfing of flowers. Factors such as reproductive biology and environmental conditions at vegetative and reproductive stages bring variation in the extent of gene flow. Cultivars with open florets during pollination may have increased gene flow. High or low humidity or temperature during anthesis may decrease gene flow. Although pollen movement has been observed 1000 m from the source, substantial outcrossing beyond 30 m was not observed. Rigorous and systematic gene flow studies in wheat are absent from the scientific literature. Gene flow data could establish an appropriate isolation distance between cultivars and genetically modified (GM) plants or hybrids.