Eleven novel polymorphic microsatellite loci were developed and characterized for the recently validated roundscale spearfish Tetrapturus georgii. Characterization of these markers, based on 35 roundscale spearfish from the western North Atlantic, revealed two to 21 alleles per locus with an average expected heterozygosity (HE) of 0·09–0·94, and all loci conformed to Hardy–Weinberg expectations. Cross-amplification of these 11 loci against all other eight known istiophorid species indicates promising prospects for the utility of these markers for istiophorids in general.