The invention relates to a reciprocating-piston internal combustion engine (1) having at least one engine cylinder (2, 3) and at least one piston oscillating therein, and having at least one balancing mass (14) which is driven in an oscillating manner by a crankshaft (11) via a crank throw (15) and a compensating connecting rod (16), and which is guided in a translatory fashion by means of a linear guide (17) assigned in each case to the respective balancing mass (14). The linear guide (17) is formed by at least two guide elements (18, 19), which are spaced apart from one another, for the balancing mass (14). A bearing (23) for articulatedly connecting to the compensating connecting rod (16) is formed on the balancing mass (14) in a central portion between the two mutually spaced apart guide elements (18, 19). A mass balancing system is thereby created, which ensures as high a degree of running smoothness as possible, in particular as low a level of vibration as possible, and which at the same time can be realized in as cheap and practicable manner as possible.