The transfer of herbicide resistance genes via pollen-mediated gene flow from genetically engineered (GE) crops to non-GE crops is of relevance for ensuring coexistence of different agricultural cultivation forms as well as for weed management.  Co-existence in oilseed rape (Brassica napus) depends on the development of management strategies to keep the adventitious presence of GE plant material below the EU labeling threshold of 0.9% in non-GE harvest products.  Crop-to-crop crossfertilization is one source of adventitious GE presence.  Several field experiments have been conducted to evaluate pollen-mediated intraspecific gene flow from herbicide resistant to nonresistant oilseed rape.  We have performed a literature search for worldwide studies on cross-fertilization in oilseed rape1 to identify the major factors affecting pollen-mediated gene flow.