We investigated the genetic diversity of the southern flounder Paralichthys lethostigma. Microsatellite-enriched libraries were constructed and novel microsatellite markers were developed and applied for genetic detection of wild populations. Cross-species amplification was also conducted in five pleuronectiforme species. Of 45 randomly selected and sequenced clones, 43 contained a CA or GA repeat motif. Fourteen pairs of primers were designed to investigate the polymorphism and genetic structure of a wild population collected from North Carolina State coastal waters. Two loci were monomorphic and 12 loci were polymorphic. The number of alleles per polymorphic locus ranged from 2 to 16, with an average of 7.3, and the expected heterozygosity per locus ranged from 0.10 to 0.92, with an average of 0.58. Cross-species amplification showed that most of the markers could successfully amplify Paralichthys olivaceus DNAs, few markers amplified in Verasper variegatus and Verasper moseri, and none of them could amplify Scophthatmus maximus and Cynoglossus semilaevis DNAs. The isolated polymorphic markers would be useful for the genetic breedingand assessment of genetic variation within the genus Paralichthys.