We isolated and characterized nine polymorphic microsatellite loci from the great scallop (Pecten maximus) as part of an attempt to better understand the population–genetic structure of this species. Levels of genetic diversity were assessed in 32 scallops collected from the coastal waters of Port Erin Bay, Isle of Man. The number of alleles ranged from two to 29 and observed and expected heterozygosities varied between 0.031 to 0.906 and 0.062 to 0.973, respectively. Two loci showed significant (P < 0.05) heterozygote deficits, likely because of null (nonamplifying) alleles; one pair of loci was in linkage disequilibrium.