We review recent publications involving molecular biology and heart failure. There was some further evolution in our knowledge of the basis for the simplest of molecular genetic diseases--single gene disorders. This year, hypertrophic cardiomyopathy had further genes identified as causative mutations; was shown to have the same genetic defects in spontaneous and familial cases; and demonstrated phenotypic alteration by environmental factors. Several rare cardiomyopathies were linked to the dystrophin gene, previously identified as the mutated gene responsible for forms of muscular dystrophy. Molecular methods were applied to linking viral infection to dilated cardiomyopathy by hunting for viral genomes in heart muscle, and for seeking mutations in mitochondrial DNA. Molecular treatment of restenosis after angioplasty showed promise through the application of gene transfer to vascular tissue by oligonucleotides as well as adenovirus-mediated gene transfer. The ethical aspects of diagnosing and treating human disease using genetic information, which receive frequent discussion in print, are also reviewed.