Premise of the study: Nuclear microsatellite markers were developed in the fen specialist moss, Scorpidium cossonii, to study genetic diversity and genetic structure of this species in relation to land-use types, habitat fragmentation, and habitat conservation measures. Methods and Results: The polymorphisms of 14 microsatellite markers were characterized. All primers were tested on 140 gametophytes collected from four populations in Switzerland. The primers amplified di- and trinucleotide repeats with three to 26 alleles per locus. The primers worked also in the two other species of the genus: 14 and 12 primers successfully amplified in S. revolvens and S. scorpioides, respectively. Conclusions: In future studies, our primers have the potential to provide valuable information on genetic diversity, genetic structure, and on historical and recent gene flow in S. cossonii; they should also enable related research in other Scorpidium species.