Genetic polymorphisms were investigated in fishers (Martes pennanti) using horizontal starch gel electrophoresis of allozymes. During the 1996–1997 fisher trapping season muscle and liver samples were collected from animals in New Hampshire, New York, Wisconsin, and West Virginia, whereas blood samples were collected from New Hampshire and New York animals only. A total of 30 gene loci were resolved from muscle, liver and blood samples. For the entire pooled sample, the mean multilocus heterozygosity (direct count) was 0.047 and the percentages of loci polymorphic (0.95 criterion and 0.99 criterion) were 20.8 and 45.8, respectively.