The DNA-ploidy of the left and right ventricular wall in 48 patients aged 80-98 years was investigated by scanning cytophotometry. The great variation in nuclear ploidy previously described in the heart muscle was shown to persist during the ninth decade. In addition, the percentage of nuclei with more than 2C DNA content in both ventricles correlated with the degree of coronary stenosis, and in the right ventricle with the presence and severity of pulmonary emphysema, and with the duration of digitalis therapy where this drug was given.