Rubus alceifolius Poir. (Rosaceae) was introduced into La Reunion island in the mid 19th century. Probable origins and precise time of its introduction are not well known. Some sources suppose that this bramble was introduced from Southeast Asia. others suggest that it may have first been introduced into Madagascar. This bramble has become a serious weed in native vegetation. The development of a biological control program is now being planned. Prior to develop this biological control, we must first characterise the genetic diversity of the plant in every area of introduction and in native range. To estimate genetic diversity, 254 specimens of Rubus spp. were sampled within the area of introduction (La Reunion, Mayotte, Mauritius, Madagascar, Australia), and within its native range (Thailand, Laos, Vietnam, Sumatra and Java). The technique we used is Amplified Fragment Length Polymorphism. A matrix of distance between individuals was calculated according to the Simple Matching distance, and a tree was constructed according to the Neighbour-Joining Method. In the tree, two well-separated groups are observed for Rubus alceifoliue. In the first one, all provenances from within the native range are grouped. This group is characterised by a relatively high genetic diversity among individuals of the sarne locality. The second group includes all provenances from within tile area of introduction. In this group, intralocality variation is reduced, except for Madagascar, where polymorphism is comparable to that in populations from the native range. The considerable separation between populations in the area of introduction and these from the native range, the intermediate position of individuals from Madagascar, and the lack of variability within each locality in the area of introduction, yield on the origins of introduced Rubus alceifolius. The reasons for insights a lack of polymorphisrn within each locality in the area of introduction are now being investigated.