Abstract: In a process for determining the cell propagation time between two arbitrary test points in an asynchronous network, specifically an ATM network, as well as a device for performing this process, the cell propagation time between two test points using two free-running clocks, i.e., non-synchronized clocks, is determined. For this purpose, a plurality of test cells are transmitted bidirectionally between the two test points and the respective send and receive instants are measured and recorded. With the help of a linear regression analysis of the measured send and receive instants, the time and frequency offsets between the two clocks can be estimated. The cell propagation time is then determined from the estimated frequency offset, the estimated time offset, and the measured send and receive instants of a selected test cell traveling in the upward and/or downward direction.