Tissue samples taken during surgery for therapeutic reasons from patients with acquired valvular heart disease (a.v.h.d.) were examined for collagen ultrastructure evaluation. The case material was obtained from 26 patients, and samples from the following organs were evaluated: palatine tonsils, mitral and aortic valves, heart auricle, skeletal muscle, periodontium and subcutaneous tissue. The examinations revealed the presence of general collagenopathy in a.v.h.d. The authors believe that examinations of the connective tissue ultrastructure may be useful and important in diagnostics and prophylaxis of a.v.h.d.