In this paper, the PAE of tube voltage of 93 diagnostic X-ray units those are using at the 19 general hospitals and 9 local clinics in the area of Sungnam, Inchun, and Seoul have been surveyed. The results are summarized as following. 1. PAE of tube Voltage 70, 100KV at the 56 (60%) X-ray units were ${pm}7%$ below, at the 8 units (9%), were ${pm}7%$ above, and those 29 X-ray units (31%) were ${pm}7%$ below or above with the 70, 100KV tube Voltage in a unit. 2. PAE ${pm}7%$ below were 68 X-ray units, at the low tube voltage (70KV), and 76 X-ray units at the high tube Voltage (100KV). 3. For six year-use abofe, used X-ray units were PAE ${pm}7%$ above, and so, the longer used years the more X-ray units became declined in those performance. 4. PAE of tube Voltage were better efficiency at the large capacity 30 X-ray units than small capacity 10. 5. PAE ${pm}7%$ abovein were only 8 units among 84 diagnostic X-ray units in the general hospitals.