Tubes are directed to a filling station (15) for filling the tubes (T) in a tube-filling machine, and, in the filling station, a liquid or highly viscous product (P) is poured into the tubes by means of a filling apparatus (16). Each tube is also weighed and the actual weight is compared with a desired weight. The filling apparatus is adjusted if the variance between the actual weight and the desired weight lies outside predetermined limits. In the process, the weighing of the tubes in the tube-filling machine occurs within 5 sec. after the end of the filling operation, either already in the filling station or between the filling station and an ejection station (22) for bad tubes (T′).