Dilated cardiomyopathy (DCM) is a heart muscle disorder characterized by atrial and ventricular dilation often with relative wall thinning, severe systolic and diastolic ventricular dysfunction, and frequent findings of heart failure. Using genetically engineered mice, a number of studies have attempted to determine the role of specific genes, as well as to mimic the phenotype of human DCM. Naturally occurring and acquired animal models of DCM also have been investigated. In this brief review, we will focus on small animal models of DCM, particularly those in the mouse, together with some comments on the autosomal-recessive cardiomyopathy of the hamster. These animal models can be categorized into several general groups in accordance with the presumed role of the gene mutation involved, including intrasarcomeric and extrasarcomeric cytoskeletal abnormalities, which resemble some forms of hereditary human DCM, and overexpression or disruption of genes that control molecules participating in intracellular signaling pathways, including the β-adrenergic system and calcium regulation. Modifications in the latter two pathways can cause or alleviate DCM in animal models, suggesting their importance in myocyte adaptive and survival mechanisms.