The objective of this study was to establish the mode of inheritance of bovine dilated cardiomyopathy (BDCMP). We analyzed a pedigree comprising 75 animals in three age classes and five diagnostic classes based on clinical and pathological findings using the Pedigree Analysis Package. Segregation analyses were performed under three models, a major gene model, a mixed model, and an environment model. Under each model three data sets were analyzed. In the first data set, only animals with clinically manifested BDCMP were considered affected; in the second data set, animals with no clinical findings but with strong pathological evidence were included in the group of affected animals; and in the third data set, this group was extended to include animals that were suspected of having BDCMP. For all three data sets, a recessive allele at a single biallelic major locus controlling the underlying liability fitted the data best. Based on Akaike's information criterion, the major gene model was the most efficient model in all data sets. We conclude that a single biallelic major locus is likely responsible for the disease.