A map for the interactions of the major proteins from Potato virus A (PVA) and Pea seed-borne mosaic Virus (PSbMV) (members of the genus Potyvirus, family Potyviridae) was generated using the yeast two-hybrid system (YTHS), Interactions were readily detected with five PVA protein combinations (HC-HC, HC-CI, VPg-VPg, Nla-Nlb and CP-CP) and weak but reproducible interactions were detected for seven additional combinations (P 1-CI, P3-Nlb, NlaPro-Nlb, VPg-Nla, VPg-NlaPro, NlaPro-Nla and Nla-Nla), In PSbMV, readily detectable interactions were found in five protein combinations (HC-HC, VPg-VPg, VPg-Nla, Nla-Nla and Nla-Nlb) and weaker but reproducible interactions were detected for three additional combinations (P3-Nla, Nla-NlaPro and CP-CP), The self-interactions of HC, VPg, Nla and CP and the interactions of VPg-Nla, Nla-NlaPro and Nla-Nlb were, therefore, common for the two potyviruses, The multiple protein interactions revealed in this study shed light on the co-ordinated functions of potyviral proteins involved in virus movement and replication.