Quantitative nuclear cardiography was applied to 400 patients with valvular heart disease proven by heart catheterisation. The study yielded the following results: 1. The parameters used were directly related to th4 cardiac index, the enddiastolic volume of the left ventricle and the pressures in the pulmonary vascular system. 2. The method proved to be highly sensitive in stating whether there was a hemodynamically effective valvular disease present or not. Differential diagnosis, however, was not possible. 3. The prolongation of the circulation times correlated with the hemodynamic severity of the disease. 4. The method could be used in evaluation of corrective surgery and for follow-up after operation.