An attempt to give art historians and restorers interested in x-ray techniques a brief introduction to the subject without going into details of the physics involved. The first x-ray photographs of paintings date from 1896. The technique's use on paper, paintings, musical instruments, furniture, weapons, ceramics, mummies, bronze sculptures and for in-situ examination of archaeological sites is summarised. Details are given of choice of film and variations in technique which take into account thickness and other aspects of the object being photographed. Diagrams, graphs, references.