Familial hypertrophic cardiomyopathy is the first primary cardiomyopathy to have yielded to the techniques of modern molecular genetics. In the past few years, four genes responsible for this disease have been identified, all of which code for sarcomeric structural proteins. In addition, structure-function analysis and genotype-phenotype correlation studies have shed significant light on the molecular basis of this disease. It is hoped that within the next few years the application of molecular genetic tools will not only facilitate the diagnosis of hypertrophic cardiomyopathy but will also provide prognostic and therapeutic stratification for more definitive therapy.