Described are method and apparatus for diagnosis of liquid losses in pressure measuring transducers filled with pressure transmitting liquids. Such pressure measuring transducers include a pressure sensor (3) arranged in a pressure measuring chamber (1), and a pressure transfer means (5) connected to the pressure measuring chamber (1) and sealed against external surroundings by a separating diaphragm (7), on which a pressure to be measured acts in measurement operation. A sealed inner space (15) thereof is composed of the inner spaces of the pressure transfer means (5) and the pressure measuring chamber (1) and is filled with a pressure transmitting liquid (17), which, in measurement operation, serves for transmitting pressure acting on the separating diaphragm (7) to the pressure sensor (3). Such pressure measuring transducers further includes an apparatus for detecting liquid losses (L). The apparatus for detecting liquid losses (L) includes a test element (25) arranged in the sealed inner space (15). The outer volume of the test element (25) is reducible for diagnosis of liquid losses (L). The apparatus for detecting liquid losses (L) further includes an evaluating unit (29), which serves, during diagnosis, for registering, as a function of a volume reduction (ΔV) of the test element (25), a pressure (p) measured by the pressure sensor (3), and, on the basis of this pressure (p) measured as a function of the volume reduction (ΔV), for detecting whether liquid (17) has escaped.