In the present work, EST-SSR (expressed sequence tag-simple sequence repeat) loci were obtained by screening 45 000 ESTs from the Pacific white shrimp Litopenaeus vannamei, which was available in a database of the ShEST (Shrimp EST Genome Project) consortium. Fifty-two of 600 EST-SSR loci were selected. From this total, 21 EST-SSRs were polymorphic among 40 individuals and had their gene products ascribed. Two to 20 alleles per locus were detected and the observed heterozygosity ran-ged from 0.15 to 0.86. Eight loci presented a sig-nificant heterozygote deficit after the Bonferroni correction, which was attributed to null alleles. Seven loci were able to have their protein prod-ucts, molecular functions and biological processes determined. Our results are promising for future studies that relate the levels of these gene poly-morphisms with different biological responses to stress in aquaculture.