The present invention relates to a device for displaying X-ray images of an object, preferably in connection with surgical orthopaedic operations, wherein X-ray images of the object are generated by means of at least a first and a second X-ray device ( 19, 20 ). The first X-ray device ( 1 )=is provided to X-ray the object in a first plane (P 1 ) and the X-ray images obtained thereby are displaced on a first screen ( 28 ) and the second X-ray device ( 20 ) is provided to X-ray the object in a second plane (P 2 ) and the X-ray images obtained thereby are displayed on a second screen ( 30 ). An automatic image changing device (AC) includes an image alternator ( 54 ) which is provided to automatically change the display of moving images of the object taken in one plane (P 1 ) on the first screen ( 28 ) to display of moving images of the object taken in the other plane (P 2 ) on the second screen ( 30 ) and vice versa, such that it becomes possible to see moving X-ray images of the object taken in the two different planes (P 1 and P 2 ) close behind each other. Each receiver ( 22 and 24 respectively) in each X-ray device ( 19 and 20 respectively) is linearly displaceable relative to the associated transmitter ( 21 and 23 respectively) and/or each transmitter ( 21 and 23 respectively) is linearly displaceable relative to each receiver ( 22 and 24 respectively) for varying the distance between each receiver ( 22 and 24 respectively) and transmitter ( 21 and 23 respectively).