Apparatus for recording data on X-ray films which are stored in cassettes having windows for exposure of certain portions of films therein includes a housing with two slots for insertion of cards with information pertaining to the patient and/or physician. The housing confines a battery of liquid crystals and an associated digital clock, digital calendar and digital counter each adapted to be actuated from the exterior of the housing to cause the corresponding liquid crystals to furnish the selected information. Such information, together with information on one of the cards, is imaged onto the exposed portion of X-ray film in the properly inserted cassette by a partly light transmitting mirror and an optical element. The images of the liquid crystals are inverted depending upon whether the X-ray film bears a postero-anterior or an antero-posterior picture of a patient's chest to thus ensure that the recorded data can be read while the physician looks at the developed film in a manner as is customary for examination of X-ray pictures. The liquid crystals can be illuminated by a discrete light source so that the light source which illuminates the data cards inserted into the housing need not be selected with a view to properly illuminate the liquid crystals and vice versa.