A method of operating a motor vehicle drive-train having a drive aggregate, a group transmission and a drive output. The aggregate can couple an input shaft of the transmission which includes main, splitter and range groups. To carry out a shift, a target gear and target rotational speed of the aggregate are calculated for the shift to be carried out. After the initiation of the shift a load reduction is first carried out, then a group of the transmission is disengaged in order to shift the transmission to neutral, after which a group of the transmission is synchronized and to shift out of neutral, the synchronized group is engaged, and then the load is again built up. Initiation of the shift, after calculating the target gear and the target rotational speed, occurs at a point in time when complete performance of a shift is not yet possible.