Jack-jumper ant venom proteins were etectrophoretically separated on SDS-polyacry-lamide gels, transferred to nitrocellulose and probed with sera from subjects who had experienced an allergic reaction after being bitten by a jack-jumper ant. Ant venom components that bound IgE antibodies were detected by addition of 125I-anti-human IgE followed by autoradiography. Of the 17 polypeptides resolved by electrophoresis only three, of molecular weights approximately 14 kD, 12 kD and 10 kD, bound IgE antibodies from the panel of 50 sera examined. There was a marked similarity in the binding patterns by individual sera with almost all of the sera recognizing the 14 kD and 12 kD components. IgE-binding profiles of separated ant venoms from ants collected in different regions of Australia appeared to be very similar if not identical. Identification of the ant allergens is a necessary prelude to the preparation of standardized venom sac extracts suitable for safe and effective diagnostic and therapeutic use.