A key to the species of Hymenoptera that parasitize insects feeding on sunflower seed heads is presented. The data base for this work is from rearings done in mid-western Canada but the key should be reliable throughout North America. A discussion of each parasitoid, giving host records, distribution, references, and a morphological diagnosis, is presented. Finally, a list of all of the species of parasitic Hymenoptera associated with sunflower in North America is given including important references.