Background: Medical x-rays are the largest man-made source of public exposure to ionizing radiation. It is important to avoid conditions where the amount of radiation used is more than that needed for the procedure.

Materials and Methods: The Entrance Skin Exposure (ESE) measurement was conducted for quality control of x-ray machines and survey of operator’s experimental techniques. The ESEs were measured by UNFORS dosimeter for five common types (12 projections) of x-ray procedures in standard man for the 18 public hospitals of Yazd province.

Results: The median, 3^rd quartile, minimum, and maximum values of each ESEs distributions are reported. The 12 histograms are presented showing wide distribution of measured ESE in each examination. The survey results are compared with guide levels that reported by CRCPD or NRPB. The sum of ESEs measurements such as in skull, Th-spine and L-spine are projection out of the guide levels. One of reasons of the wide ESEs distribution is miss unique role in selection of techniques for the same procedure and same patient size by operators in each center and even for one x-ray machine.

Conclusion: The findings support the importance of the on-going quality assurance program to ensure doses are kept to a level consistence with optimum imaging quality. Iran . J. Radiat. Res., 2004 1(4): 199-204