Abstract The pink shrimp (Farfantepenaeus duorarum) is an ecologically and economically important penaeid species in the southeastern United States. The biological and economic importance of this species prompted us to conduct a molecular genetic assessment of pink shrimp genetic diversity and population genetic structure. We sequenced a 558-base portion of the mitochondrial DNA (mtDNA) control region from pink shrimp collected at five locations ranging from North Carolina to south Texas. Haplotype and nucleotide diversity values in pink shrimp are among the highest yet reported for decapods. In our samples, all haplotypes were unique, and the average nucleotide diversity was approximately 2%. Nucleotide divergence between haplotypes ranged 0.2–3.9%. A mismatch analysis produced a unimodal distribution of pairwise differences between haplotypes that is consistent with a historic rapid population expansion. A population expansion, high mutation rate in the control region, and large population size all prob...