A coaxial plug-in connection, particularly for printed circuit boards. An outer and inner conductor are assigned to each board, and can be electrically connected to the outer or inner conductor of the other respective board via a sleeve-shaped plug-in adapter coupling that encompasses a corresponding outer conductor portion and an inner conductor portion. The inner conductor of the printed circuit board is a spring metal sheet, one end of which is fixed to the board or an insulating element, while the other end is free to engage with the inner conductor portion of the plug-in coupling, which is configured as a contact pin.