Genetic variabilities within and between Finnish populations of Golden Retrievers, German Shepherds, Wirehaired Dachshunds, Pembroke Welsh Corgis and Bedlington Terriers were quantified with microsatellite allele numbers, observed heterozygosities, expected heterozygosities, __F__IS estimates, __F__ST estimates and __D__S distances. In a sample of 50 individuals from each breed and ten polymorphic loci, the highest genetic diversity was exhibited in the Wirehaired Dachsunds and lowest in the Bedlington Terriers. Although statistically significant deviations from the HardyβWeinberg (HβW) equilibrium were observed, they occurred at an unexpectedly low frequency. Most strikingly, the extremely small Bedlington Terrier population displayed genotypes in HβW proportions in all investigated loci. The HβW deviations always occurred with positive __F__IS estimates, which, on average, were not larger than values reported for freeβliving canids. Genetic differentiation between the breeds was very large. As a comparison, present estimates were, on average, over two times higher than previously observed between breeds of sheep, and over two times higher than the highest estimates reported between human populations. Moreover, the highest __D__S distances were only slightly lower than the lowest values inferred between humans and chimpanzees. Severe bottlenecks in the recent past of the examined breeds were not statistically supported. The presented data imply genetic isolation and intense artificial selection in the history of these breeds of dogs.