Abstract: The invention relates to a surgical bone-drilling device (1) comprising a drill (3) connected to a drive (2), a container (4) for a coolant (5), at least one pump (6) for delivering the coolant (5), a first conduit (7) for delivering the coolant (5) from the container (4) into the interior of the drill (3), and a second conduit (8) for delivering the coolant (5) from the container (4) to the outside of the drill (3), and also a handpiece (19), a drill guide (20), and a cooling method for such a bone-drilling device (1). To improve the cooling action, a measuring device (9) is provided for detecting the drilling depth (?d) of the drill (3), which measuring device (9) is connected to a control device (10) for controlling transport of the coolant (5), such that the quality of the coolant (5) in the first conduit (7) and in the second conduit (8) can be controlled as a function of the drilling depth (?d) of the drill (3).