Interspecific F1 hybrids of Peromyscus maniculatus (deermice) and P. polionotus (oldfield mice) were backcrossed to P. maniculatus. Backcross progeny were electrophoretically typed for 11 variant protein markers: albumin, transferrin, leucine aminopeptidase, amylase, 6-phosphogluconate dehydrogenase, nucleoside phosphorylase, dipeptidase, tripeptidase, glutamate oxaloacetate transaminase, alcohol dehydrogenase, and sorbitol dehydrogenase. Genetic variation for each protein was attributed to a single autosomal locus. The alcohol dehydrogenase (Adh), salivary amylase (Amy), and albumin (Alb) loci appeared to be linked in the sequence of Adh-11.5 cM-Amy-33.3 cM-Alb. The tripeptidase locus, Pep-2, also may be loosely linked to Alb in this group. Variants at all other loci assorted independently. These and other known linkage relationships in Peromyscus correspond closely to those of the house mouse, Mus musculus. The available evidence in Peromyscus further supports the concept of linkage conservation by natural selection.