In a method for operating an internal combustion engine (10) equipped with a piston pump as a high-pressure pump (18), which is driven by a drive shaft (28) of the engine (10), in which the high-pressure pump (18) delivers fuel from a low-pressure region (16) to a high-pressure side (38) and a quantity control valve (44) sets the quantity of fuel delivered by the high-pressure pump (18), the acoustic emission of the high-pressure pump is reduced by virtue of the fact that the high-pressure pump (18) functions in a two-point operation, alternating between full delivery for individual or successive piston strokes and idle delivery for individual or successive piston strokes and, when the pressure falls below a lower pressure threshold, the full delivery is activated until an upper pressure threshold is reached.