Abstract: Both indigenous and exotic natural enemies are used in commercial biological control to reduce pest populations. As exotic biological control agents could have a negative impact on non-target organisms and may threaten local biodiversity, their use is not without risks. In the framework of a project funded by the Belgian authorities, the proportion of exotic organisms of the total assortment of invertebrate biological control agents that is commercially available to Belgian growers was estimated. The products of European producers were inventoried and the original distribution of the species listed was investigated. The survey indicated that currently more than 90 species of invertebrate natural enemies are commercially available and that about 53% of these are exotic to Belgium or to neighbouring countries within the same ecoregion. All continents were found to deliver more or less 20% of the exotics (Asia: 17%, Africa: 20%, North America: 17%, Oceania: 17%, Europe: 24%), with the exception of South America that delivered only 5% of the exotics. The European natural enemies that have not previously been described from Belgium or surrounding areas mostly have a Mediterranean origin.