Previous research had shown that the diploid S. vernei clone EBS181 contained at least two genes for resistance to the golden nematode. Resistant tetraploids obtained by backcrossing to tuberosum clones, with selection against Race A, possessed only one gene. Crosses between these tetraploids produced evidence that at least two genes exist within this set of tetraploids. Crosses between tetraploids with resistance from vernei EBS181 and tetraploids with resistance from andigena CPC1673 produced results that can be explained by one of the genes from EBS181 segregating at the same locus as the one from CPC1673. © 1973, Springer. All rights reserved.