We have investigated the performance characteristic of the heavy metal filters with higher atomic numbers by comparing their patient exposures, tube loadings, radiographic contrasts, and noise Wiener spectra with those of a combination of copper and aluminum filter which has been used widely in chest radiography.<BR>Seven heavy metal filters were used for this study. As for a tungsten filter, two filters different in thickness were used. One is 0.05 mm thick, and the other 0.10 mm. The other metal filters were respectively combined with a tungsten filter with a thickness of 0.05 mm.<BR>Among the all filters investigated, tube loading of tungsten filter with 0.05 mm thick is minimum. Tungsten with 0.1 mm thick and tungsten with 0.05 mm + barium show the larger advantages in patient exposure than those of the other filters.<BR>It was found that the magnitude of patient exposure varied slightly wit h the difference of image receptor used. The use of heavy metal filters showed the small advantages in the patient exposure reduction (-20%) compared with that of conventional copper filter. The use of heavy metal filters showed increasing tube loading (-5times) compared with that of conventional copper filter. Noise Wiener spectra of heavy metal filters showed comparable with those of conventional copper filter.<BR>In conclusion, the use of heavy metal filter combinations offer no significant advantages over optimal conventional filters.