Several canine cDNA libraries were screened with human beta-galactosidase cDNA as probe. Seven positive clones were isolated and sequenced yielding a partial (2060 bp) canine beta-galactosidase cDNA with 86% identity to the human beta-galactosidase cDNA. Preliminary analysis of a canine genomic library indicated conservation of exon number and size. Analysis by Northern blotting disclosed a single mRNA of 2.4 kb in fibroblasts and liver from normal dogs and dogs affected with GM1 gangliosidosis. Although incomplete, these results indicate canine GM1 gangliosidosis is a suitable animal model of the human disease and should further efforts to devise a gene therapy strategy for its treatment.