Familial hypertrophic cardiomyopathy (FHCM) is characterized by an autosomal dominant transmission, left ventricular hypertrophy and myocardial disorganization. So far, 13 genetic loci and more than 130 mutations in ten different genes have been identified. Recent study suggested impaired force production associated with inefficient use of ATP as the main disease mechanism. We performed haplotype analysis with the use of microsatellite markers linked with beta-myosin heavy chain, troponin T, alpha-tropomyosin and cardiac myosin protein C genes in three Polish families with hypertrophic cardiomyopathy (23 individuals). This method is based on the analysis of distribution of the disease in the family and the alleles of chosen microsatellite markers. In two families, the disease was associated with beta-myosin heavy chain gene. We also found a genetic carrier of the mutated gene among children of the patients. In one family the connection of the disease with the mutation in alpha-tropomyosin gene was confirmed, no sudden cardiac deaths were recorded and the degree of myocardial hypertrophy was small.