Twelve polymorphic microsatellite DNA loci were isolated from the brown crab, Cancer pagurus L., by construction of microsatellite-enriched genomic libraries. Genotyping of 40 individuals from Norfolk (UK) revealed variable levels of locus polymorphism with an average of 7.75 alleles per locus (range 2-22). The observed and expected heterozygosities per locus ranged from 0.025 to 0.868 and from 0.025 to 0.947, respectively. No evidence of linkage disequilibrium was detected between pairs of loci and genotype proportions at all loci conformed to Hardy-Weinberg equilibrium expectations. The microsatellite loci developed constitute a suite of genetic markers applicable to numerous areas of C. pagurus research.