The stable chromosome aberrations of medical diagnostic X-ray workers were analyzed using G-banding and evaluated their accumulative doses. The results showed that the frequencies of reciprocal translocation

stable aberration and total aberration among the 4417 metaphase spread from 44 cases of medical diagnostic X-ray workers were distinctly higher than control values (P<0.05~0.005). The stable aberration predominated strikingly in total aberration and reciprocal translocation was 57% in the stable aberrations. The medical diagnostic X-ray workers were divided into 3 groups according to calendar year of entry. The data showed that the frequencies of total aberration

stable aberration and reciprocal translocation incerased with working years

especially in two groups who started working before 1970

there are statistically significant differences between the calendar year of entry before 1660 and 1960~1969 in X-ray workers and control group. According to the equation recommended by straume

linear coefficient (α) in linear quadratic model recommended by Schmid and the transformation coefficient by Lucas. The accumulative doses calculated are 0.58

0.37 and 0.07 Gy for calendar year of entry before 1960

960~1969 and after 1970 in X-ray workers

respectively.