Phodopus sungorus, the Siberian dwarf hamster, exhibits a number of reproducible and quantifiable behavioral changes when the members of a male-female pair bond are separated. Preliminary evaluation of the syndrome revealed a significant increase in body weight, decrease in social interaction, and decrease in exploratory behaviors, which occurred predominantly in separated males. Some, but not all, of the behavioral effects of separation are reversed by the tricyclic antidepressant, imipramine. Separation of pair-bonded Siberian dwarf hamsters may provide a new animal model for depression, incorporating the practical advantages of a rodent model with the conceptual advantages of a naturalistic life event precipitant.