Resistance to white lupin mosaic virus (WLMV), a recently characterized member of the potyvirus group, was found in pea (Pisum sativum L.) plant introductions from Ethiopia (PI 193835) and India (PI 347485). In cross and backcross populations between plants of resistant PI 193835 with those of susceptible 'Bonneville' and PP-492-5, this resistance was demonstrated to be governed by a single recessive gene. This gene was distinct from other genes previously found in PI 193835 and PP-492-5 (from PI 347492, India) conferring resistance to clover yellow vein virus (CYVV) and three strains of pea seedborne mosaic virus (PSbMV). Indirect evidence suggests that this newly recognized viral resistance gene, wlv, is a member of a cluster of closely linked genes located on chromosome 6. This gene cluster includes sbm-1, sbm-3, and sbm-4, which govern resistance to three PSbMV pathotypes, and cyv-2, which governs resistance to CYVV.