Familial Hypertrophic Cardiomyopathy (FHC) is a genetically inherited disorder of heart muscle. Over the past 40 years many studies have been done to describe in detail the clinical presentation of this disease and its associated pathophysiological consequences. The primary focus of this review is to discuss more recent studies involving the genetic mapping of one locus on chromosome 14, which causes FHC, and then to summarize studies demonstrating that this locus contains mutations in the cardiac myosin heavy chain genes. The chromosomal location of other putative FHC loci will also be considered. Finally, the implications of results that demonstrate that cardiac myosin heavy chain defects produce the pathophysiology of FHC will be considered from both clinical and basic research perspectives.