The problem of invasive alien species in Namibia was highlighted 20 years ago, at the 1984 annual professional officers' meeting of the then Directorate of Nature Conservation and Recreation Resorts. A series of detailed field surveys had been undertaken nationally, and the results of these surveys were presented at this annual research meeting and subsequently published. The only other detailed studies of invasive alien species since the early 1980s were the innovative research by the Department of Water Affairs into the control of the aquatic weed, Salvinia molesta, and much more recently, research on Prosopis and black-faced impala. Until the establishment of specialist working groups under the National Biodiversity Task Force about five years ago, little more took place in the field of invasive species research other than the ongoing biological control of Salvinia molesta.