Technical Abstract: Sixty-six watermelon disease resistance gene analogs (WRGA) were isolated from genotypes possessing disease resistance to fusarium oxysporum f. sp. niveum races 0, 1, and 2, zucchini yellow mosaic virus, papaya ringspot virus watermelon strain, cucumber mosaic virus, and watermelon mosaic virus. Degenerate primers were used to amplify the nucleotide binding site (NBS) from NBS- leucine-rich repeat (LRR) resistance gene analogs. Alignment of deduced amino acid sequences revealed that motifs of Drosophila Toll and mammalian interleukin-1 receptor (TIR) and non-TIR NBS-LRR genes were present. Using cluster analysis of the amino acid sequences, eight WRGA groups were identified and markers were created for each WRGA group. Linkage mapping of markers designed from sequences from three WRGA groups placed the WRGA all on linkage group XIII. The use of the WRGA markers as well as other markers on the XIII region may be useful in marker-assisted selection for improvement for disease resistance in watermelon.