Left ventricular (LV) volumes were assessed densitometrically by measuring the mean logarithm of the gray level (MLG) of a fixed region of interest, which includes the LV silhouette at end-diastole. Stroke volumes were obtained from calculating the MLG difference between diastole and systole without using contrast material. The results were significantly lower than those obtained by the area-length method. The ejection fraction was derived from the MLG difference between two consecutive diastoles after intravenous injection of contrast material. The results were well correlated with those calculated by the area-length method.