Tobacco products (2), typically cigarettes, are manufactured on a line (1) including a cigarette maker (3) and a filter tip attachment machine (4), both equipped with a number of production devices and units connected to respective master control units (82, 83) and visual display units (84). Key characteristics of sample tobacco products (2) are tested by an auxiliary inspection unit (45) forming part of a monitoring and control system associated with the manufacturing line (1), and connected up to a common interface network (48) so that signals reflecting the monitored characteristics can be fed back to a number of control units (81) associated respectively with the devices and the units of the line (1) on which the characteristics in question depend, and programmed to pilot corrective actions in response to the feedback signal.