In this paper we describe a new, selective approach to identify protein ligand-receptor interactions between an arthropod vector and the parasite it transmits. Biotinylated vector proteins were incubated with living parasites in physiological conditions. After extensive washing, the parasites were subjected to SDS-PAGE electrophoresis and the polypeptides were electroblotted onto nitrocellulose membrane. Staining with avidin-horseradish peroxidase revealed only biotin-labeled proteins from the vector which were bound to the parasite. A multitude of tissue-specific proteins of Glossina palpalis gambiensis and G. morsitans morsitans proteins, able to bind to cultured procyclic trypanosomes of Trypanosoma brucei spp., has been demonstrated. The relevance of these interactions in relation to the developmental journey of the trypanosome in the tsetse fly is briefly discussed.