Abstract Objective—To evaluate the coding region of the cardiac actin gene in Doberman Pinschers with dilated cardiomyopathy (DCM) for mutations that could be responsible for the development of the condition Animals—28 dogs (16 Doberman Pinschers with DCM and 12 mixed-breed control dogs). Procedure—Ten milliliters of blood was collected from each dog for DNA extraction. Polymerase chain reaction (PCR) primers were designed to amplify canine exonic regions, using the sequences of exons 2 to 6 of the cardiac actin gene. Single-stranded conformational polymorphism analysis was performed for each exon with all samples. Autoradiographs were analyzed for banding patterns specific to affected dogs. The DNA sequencing was performed on a selected group of affected and control dogs. Results—Molecular analysis of exons 2 to 6 of the cardiac actin gene did not reveal any differences in base pairs between affected dogs and control dogs selected for DNA evaluation. Conclusions—Mutations in exons 5 and 6 of the cardiac actin gene that have been reported in humans with familial DCM do not appear to be the cause of familial DCM in Doberman Pinschers. Additionally, evaluation of exons 2 to 6 for causative mutations did not reveal a cause for inherited DCM in these Doberman Pinschers. Although there is evidence that DCM in Doberman Pinschers is an inherited problem, a molecular basis for this condition remains unresolved. Evaluation of other genes coding for cytoskeletal proteins is warranted. ( Am J Vet Res 2001;62:33–36)