Technical Abstract: High-resolution melting analysis after PCR allows closed-tube mutation scanning and genotyping without processing, labeled probes, real-time monitoring or allele-specific amplification. PCR is performed in the presence of the saturating dye, LCGreen® Plus, with subsequent high-resolution melting analysis on a high-throughput 96 or 384-well LightScanner®. Heterozygotes are easily distinguished from homozygotes by the shape of the normalized melting curves. On the LightScanner, the sensitivity and specificity of detecting SNP heterozygotes is 100% for PCR product lengths from 50-400 bp, and 96.7% and 98.4%, respectively, for 500-800 bps. In contrast to other scanning techniques, no separations are required. Scanning of highly variable segments of diploid organisms differentiates many genotypes, including SNP heterozygotes, double SNP heterozygotes, and homozygotes. In addition to scanning for unknown variants, genotyping of known variants is easily performed with unlabeled probes using the same system. In tetraploid organisms like the potato, unlabeled probes are a nice solution for genotyping with accurate allele dose determination. High-resolution DNA melting can be applied to diploid or polyploid organisms and requires only 5-10 minutes after PCR. Variant detection sensitivity is high and unlabeled probes allow quantitative polyploidy genotyping with a minimum of cost and effort.