Abstract: An apparatus for optical monitoring of the surface of rod-shaped smoking articles and/or filter rods for the tobacco industry comprises a conveying means transporting the rods perpendicularly to their longitudinal direction and a high-pressure lamp which serves as light source and which is connected via an optical fibre cable to a sensor block; the optical fibre cable is divided amongst at least two cross-section transformers with strip-shaped light exit regions whose light rays are directed via a further optical system from above and below respectively onto the line-shaped region of the surface of the rod. In addition the sensor block contains a row of photoelectric transducers which simultaneously the line-shaped surface region in the longitudinal direction of the rod and thereby pick up the light reflected at the surface of the rod.