An apparatus for cylinder recognition in an internal combustion engine is described, in which the individual-cylinder rpm fluctuations or variables dependent on them are first stored in memory and then, when the engine is restarted, compared with the rpm fluctuations that result at that time. From the results of the comparison obtained, a cylinder recognition can be performed. Particularly in conjunction with engines in which engine roughness detection is performed, the cylinder recognition can be done on the basis of adaptation values for the engine roughness detection.