An unusual clinical history of a 23-year-old male proband with obstructive hypertrophic cardiomyopathy associated with a rare genotype is presented. Genetic analysis of the proband found evidence for two distinct mutations of the MYH7 gene (the gene coding for the beta-myosin heavy chain): 403Arg--> Trp in exon 13 and a novel mutation, 453Arg--> His, in exon 14. A heterozygous site mutation was identified in exon 13 in the proband's father but no mutation site was found in his mother. Thus, the novel mutation in exon 14 is a de novo mutation.